Final Report Summary - CRONOS (Time dynamics and ContROl in naNOStructures for magnetic recording and energy applications)
Executive Summary:
CRONOS had one central objective, that of developing a quantitative, flexible and fully atomistic theory of ultrafast dynamics in real materials. This aimed at the creation of the necessary knowledge for advancing two technological areas crucial for the economic future of Europe: new materials for solar energy harvesting and ultra-high density magnetic data storage. In addition, CRONOS looked also at the inverse problem, namely that of engineering an optical excitation designed to produce a desired response (in standard materials science one simply studies how an excitation perturbs a materials system, but does not design specific excitations). This was done through optimal quantum control theory (OQCT).
CRONOS computational method of choice was time-dependent density functional theory, TDDFT, which we had numerically implemented in a number of mainstream codes, namely ELK, Octopus and Smeagol. The workplan was designed to encompass a full idea-to-validation pipeline and thus included: 1) formal methodological development, 2) algorithm implementation, 3) applications to both solar cells and magnetic recording, and 4) experimental validation. Importantly the software developed is distributed freely to the modeling community.
CRONOS has created the foundation of using TDDFT and OQCT to develop a better understanding of ultrafast processes in real materials, in particular related to both charge and spin-dynamics. Most importantly CRONOS has produced a complete development pipeline going from the invention of new theoretical methods, to their implementation in mainstream materials modelling packages (ELK, Octopus and Smeagol), to the use of them in problems related to solar energy harvesting and magnetic data recording, and to their validation in experiments specifically designed to address the ultrafast time scale.
CRONOS output has been published in over 140 research articles, including several in top-tier journals such as Science, Nature Photonics, etc. Furthermore CRONOS investigators have contributed to over 100 invited talks at international events, and have organized/co-organized about 20 workshops and symposia at conferences. These latter include several training activities for young researchers so that CRONOS scientists have educated about 100 young minds to time-dependent DFT and its capabilities. The general public has also been engaged by CRONOS. The various teams have featured in radio programs and popular press (both regional and international) and the coordinator has presented science to primary schools kids. All this was possible thanks to the CRONOS consortium, which comprised the European leaders in the development of ab initio computational techniques and in the production of scientific software for materials science.
CRONOS consortium includes 5 academic institutions, 3 research institutions and 1 SME, based in 7 different countries. CRONOS has been supported by 3,380,058.00€ granted by the EC through 7FP, it was coordinated by Prof. Stefano Sanvito of the Trinity College Dublin (Dublin, Ireland) and carried out by a consortium of 9 leading research institutions.
Project Context and Objectives:
CRONOS’ aim was to develop a quantitative, flexible and fully atomistic theory of ultrafast dynamics in real materials. The effort was devoted to the creation of the necessary knowledge for advancing two technological areas crucial for the economic future of Europe: new materials for solar energy harvesting and ultra-high density magnetic data storage. In addition, CRONOS explored the “inverse problem”. In fact, it did not just look at how an optical excitation perturbs a materials system (either its charge or spins) but also at how such an excitation could be engineered to produce a desired response. As such CRONOS has addressed both the “direct problem”, namely that of calculating the response of materials to perturbations, and the “inverse one”, which consists in designing the perturbations capable of producing the desired response. The theory used for the inverse problem was optimal quantum control theory (OQCT).
The computational method of choice was time-dependent density functional theory, TDDFT, which CRONOS had numerically implemented in a number of mainstream codes, namely ELK, Octopus and Smeagol. The workplan comprised 1) formal methodological development, 2) algorithm implementation, 3) applications to both solar cells and magnetic recording, and 4) experimental validation. Importantly the software developed is distributed freely to the modeling community.
WP1’s objectives were to develop and implement a full suit of technical solutions for TDDFT. These include: 1) the numerical implementation of the time-dependent Kohn-Sham equations with periodic boundary conditions to describe bulk solids in time-dependent external fields; 2) the construction and implementation of advanced meta-GGA functionals and the advanced spin-dependent XC functionals able to describe the non-collinear magnetization dynamics; and 3) the development and implementation of a TDDFT framework for the coupled electron-nuclear dynamics.
WP2’s aimed at applying the method developed in WP1 to the problem of solar energy harvesting. The problems tackled include: 1) the description of the electronic dynamics of charge transfer at interfaces; 2) the identification of both short and long-lived excitations produced by photo-induced electron transfer; 3) the construction of a unified picture of transient phenomena like excitation formation and separation; 4) the identification of the key vibrational and electronic features to optimize self-assembly of molecular components into functionally integrated systems.
The main purpose of WP3 was to establish the foundation of an electronic theory for ultrafast spin-dynamics. In particular we aimed at: 1) constructing an atomistic understanding of ultra-fast spin-dynamics in magnetic transition metals and ferromagnetic materials; 2) exploring the interplay between atomic motion and spin-dynamics in ultra-fast magnetization manipulation; 3) constructing a first step towards a multi-time approach to spin-dynamics including spin-diffusion of conducting electrons. Finally, WP3 investigates the possibility of controlling ultra-fast spin-dynamics by appropriate engineering the shape of laser pulses.
WP4 aimed at translating QOCT to TDDFT, so that to provide a fully quantistic designing tool for materials and processes. This means controlling both the electrons dynamics and also the associated nuclear one. The goal is to achieve control over 1) charge dynamics, 2) spin dynamics, 3) production of high-harmonic generation.
WP5 validated in the lab all the theoretical development achieved, focusing on: 1) the validation of theoretical modelling on solar energy conversion and spin dynamics; 2) the probing of charge and nuclear dynamics at all-organic and organic/inorganic interfaces; 3) the probing of ultrafast spin dynamics in the bulk and at interfaces of ferromagnetic/nonmagnetic film systems; 4) the design of experimental protocols for OQCT.
CRONOS main result is that of having created the foundation of using TDDFT and OQCT to develop a better understanding and control of ultrafast processes in real materials, in particular related to both charge and spin-dynamics. Most importantly CRONOS has produced a complete development pipeline going from the invention of new theoretical methods, to their implementation in mainstream materials modelling packages (ELK, Octopus and Smeagol), to the use of them in problems related to solar energy harvesting and magnetic data recording, and to their validation in experiments specifically designed to address the ultrafast time scale.
WP1 is where most of the formal development took place. On the one hand, we have implemented in both ELK and Octopus a range of tools enabling new calculations, namely periodic boundary conditions for solids and laser pulses of arbitrary intensity and shape. On the other hand, we have invented new exchange and correlation functionals for more accurate calculations of real materials. These include novel meta-GGA for quantum dots and low-dimensional structures and a spin-spiral version of the GGA for magnetic compounds.
WP2 and WP3 focused on applying the suit developed in WP1 respectively to the energy-harvesting problem and to the ultrafast magnetic recording one. These WP were strongly coordinated with the experimental WP5 and the successes of the three must be seen together. In particular, we have produced ground-breaking work demonstrating energy transfer coherence in organic solar cell materials, i.e. we have shown that during the formation of an exciton the charge density and the associated energy oscillate coherently between the donor and the acceptor. Such coherence involves nuclear motion and has been detected experimentally by ultrafast pump-probe experiments. The consequences of this work, published in Science, are reaching far beyond the solar energy arena and may impact also the biology of living being.
When looking at spin-dynamics CRONOS was able to explain the microscopic origin of the first few femtosecond of the laser-induced ultrafast demagnetization process. This consists in the establishment of spin-currents depopulating the region in proximity with the atomic nuclei, followed by a very rapid loss of magnetic moment enabled by spin-orbit interaction. A scaling law relating the spin-orbit strength and the speed of demagnetization was established and proved. Such understanding appears to be universal and can be applied to magnetic materials regardless of their macroscopic order (ferromagnetic, antiferromagnetic or ferromagnetic). Furthermore the optical response of interfaces between magnetic and non-magnetic materials was investigated and a full theory for such interfaces was developed. Also in this case the agreement with experiments is excellent and demonstrates the prediction capabilities of the methods developed.
Finally, the consortium has advanced OQCT in WP4 to a point where now predictions can be made for real systems. In particular, we are now capable of designing new lasers pulses to enhance particular regions of the high-harmonic spectrum of real molecules. This essentially means that we are capable of engineering the frequency response of real objects. A similar development took place concerning spin-dynamics for both model Hamiltonians developed for quantum dots and for bulk transition metals. Also in this case the results are extremely encouraging, although the high demand of computational resources associated with these methods need to be noted.
Overall CRONOS achieved all its targets and goals and has provided a strong development materials platform for the entire materials modelling community. Our implementations are now distributed and the codes are freely accessible.
The results of the project have been widely disseminated during the whole course of the project. CRONOS was characterized by an impressive number of dissemination actions, in particular publications and presentations of the project’s results at international events attended by the partners. The CRONOS project can count on a very wide list of publications: 130 papers were published during the entire duration of the project, while 10 are under review and are awaiting for publication. Moreover, the success of the project is demonstrated by the fact that publications were made in highly prestigious journals such as Nature (and associated journals, e.g. Nature Photonics) and Science.
CRONOS website is available at the URL http://www.insrl.eu/project/cronos/ and it will be kept alive for five years after the end of the project.
Project Results:
The consortium has met all the goals, tasks and deliverables of CRONOS’ original workplan, so that the project has to be considered fully successful. Here we report a summary of CRONOS’ main scientific achievements and then we present the identified exploitable foreground.
Scientific Achievements
CRONOS demonstrated that simulations of ultra-fast dynamics for real materials can be performed and that the results are directly comparable to experiments (typically pump-probe spectroscopy of some kind). Furthermore, some of these simulations have helped our industry partner to produce better materials for solar harvesting devices, so that theory and modelling have been demonstrated to be key elements for the delivery of progress in this space. All this was possible through a workplan encompassing the entire pipeline going from idea to software implementation, to application of the software, to experimental validation of the results. The main scientific achievements are here presented by workpackage and for a detailed description we refer to the relative deliverables.
WP1:
WP1 has constructed a suit of methodological developments aimed at improving the efficiency, accuracy and capability of TDDFT of simulating real materials. In particular it has targeted three main aspects: 1) the possibility of using arbitrary electro-magnetic pulses and of performing simulations for both molecules (open boundary conditions required) and solids (periodic boundary conditions required); 2) the construction of novel exchange and correlation functionals for both non-collinear spin and high accuracy; 3) the formulation and construction of a novel potential surfaces for combined electronic-ionic dynamics. All the developments done in WP1 have been included in the two GPL-distributed codes, Octopus and ELK.
While the implementation of arbitrary EM electro-magnetic pulses and of different boundary conditions have to be considered as technical advances, the development of new exchange and correlation functionals and of a new scheme for electron-ion dynamics have to be considered as major breakthrough.
New non-collinear exchange and correlation (XC) functional (Deliverable 1.4):
We have derived and implemented a spin-non-collinear XC functional for magnetic systems. The derivation was published in Physical Review Letters [F.G. Eich and E.K.U. Gross, Phys. Rev. Lett. 111, 156401 (2013)] while the implementation has been successfully achieved in the ELK electronic structure code. The new XC functional has been shown to improve upon the usual LDA approximation for Cr monolayer. This improvement is due to the XC magnetic field having components that are non-collinear to the local magnetization density. Note that the typical computational overheads of this functional are of the same order of magnitude of the LDA, while more complex functionals having similar qualitative features are significantly more computationally intensive.
Novel scheme for electron-ion dynamics (Deliverable 1.5):
The treatment of nuclear dynamics is indispensable for describing the physical processes underpinning both light-harvesting and ultra-fast spin-dynamics. In both cases, in fact, there is a strong interplay between electronic and ionic degrees of freedom, so that, ideally, one should treat them on the same footing. The “standard” way to take into account classical ionic motion is through the Born-Oppenheimer approximation leading to the classical Ehrenfest forces. However, for the systems investigated in CRONOS the Ehrenfest forces are not sufficiently accurate, and we have investigated whether or not one can find classical forces beyond Ehrenfest that are able to deal with non-adiabatic transitions. Indeed we have shown that this is the case. In particular we have produced three fundamental steps:
1) We have been able to rigorously define and construct classical forces beyond Ehrenfest that are able to deal with non-adiabatic transitions. These emerge from a novel approach to the coupled electron-nuclear dynamics, which is based on an exact factorization of the electron-nuclear wave function. The outcome of this analysis is the definition of a time- dependent potential energy surface (TDPES).
2) The TDPES has been tested against an exactly solvable model, providing clear evidence that the method developed provides an exact alternative description of the nuclear motion.
3) We have developed a novel mixed quantum-classical approach to the coupled electron- nuclear dynamics, which is based on the theory developed in 1) and uses the TDPES tested in 2). Again the method has been tested favorably against an exactly solvable model.
WP2+WP5:
WP2 applies all the formal development done in WP1 to the problem of solar energy harvesting. The general philosophy of WP2 was to conduct, for a number of different solar harvesting compounds, the following computational steps: 1) evaluate accurately the system geometry and exact atomic configuration; 2) evaluate the static energy levels structure; 3) perform time-dependent simulations of the energy transfer process. In addition we have developed a new solvent scheme to be used in combination with TDDFT. This is a quite crucial aspect since typical organic solar harvesting compounds are often in a solution environment. The calculations performed in WP2 were validated by experiments performed in WP5, in particular by means of ultra-fast spectroscopy.
The main highlight of WP2+WP5 concerns the study of the dynamics of both prototypical artificial light harvesting systems and technologically-relevant organic photovoltaic blends. These two works have been published in top tier journals, respectively Nature Communication [“Quantum coherence controls the charge separation in a” Nat. Commun. 4, 1602 (2013)] and Science [“Coherent ultrafast charge transfer in an organic photovoltaic blend” Science 344 1001, (2014)].
Combining high time-resolution femtosecond spectroscopy and time-dependent density functional theory, we have provided compelling evidence that the driving mechanism of the photoinduced current generation cycle is a correlated wavelike motion of electrons and nuclei on the timescale of few tens of femtoseconds. We have highlighted the fundamental role of the interface between chromophore and charge acceptor in triggering the coherent wavelike electron-hole splitting. This result has far reaching impact since it validates a large volume of scattered literature on coherent energy transfer both in the solar energy conversion field and potentially in biology.
WP3+WP5:
WP3 applies all the formal development done in WP1 to the problem of spin dynamics and relaxation in magnetic materials, with impact over the magneto-recording industry. The strategy of the combined program of WP3 and WP5 was to explore spin dynamics in: 1) finite magnetic clusters and bulk solids; 2) in magnets with different magnetic order (ferromagnetic, antiferromagnetic and ferrimagnetic); 3) across interfaces between a magnetic and a non-magnetic metal. Furthermore, since the magnetic order is very sensitive to the lattice structure of the given material, we have investigated the effect of ionic motion on the dynamics. Finally we have provided a first demonstration of optimal quantum control of the demagnetization process in a bulk magnetic material. This all represents ground-breaking work since no dynamics studies at the electronic level have ever been performed before on magnetic system. The key results from WP3+WP5 are the following:
We were able to explain the microscopic processes leading to ultra-fast demagnetization in magnetic metals, with a special focus on the first few femtoseconds of the dynamics (immediately after the exciting laser pulse has extinguished). This consists in the establishment of spin-currents depopulating the region in the proximity of the atomic nuclei, followed by a very rapid loss of magnetic moment enabled by spin-orbit interaction (there is no magnetization loss in absence of spin-orbit coupling). A quadratic scaling law relating the spin-orbit strength and the speed of the demagnetization was established and proved. Such understanding appears to be universal and can be applied to magnetic materials regardless of their macroscopic order (ferromagnetic, antiferromagnetic or ferromagnetic).
The mechanism for ultra-fast demagnetization in heterostructures made of a magnetic and a normal metal, the typical stack in magnetic recording, comprises an additional spin-relaxation channel, namely that originating from the diffusion of spin-polarized currents from the magnetic to the non-magnetic metal. Such ultra-fast mechanism, activate in thin films, has been proved experimentally with pump-probe measurements and modelled theoretically with a multi-scale approach combining TDDFT and quantum transport. The agreement between theory and experiments is excellent.
Finally, we have addressed the question on whether it is possible to exert control of the spin-dynamics by using specifically tailored laser pulses. This controllability is of major importance for future technological applications as it allows the optimization of a particular feature, while incorporating practical constraints. In particular, here we have demonstrated that laser-induced ultrafast demagnetization can be controlled by varying the intensity and frequency of the applied laser. Our work combined the mathematical framework of optimal quantum control theory (OQCT), developed in WP4, with TDDFT. By using OQCT we have optimized a laser pulse that almost doubles the relative loss of total magnetic moment in Ni as compared to a random pulse (that uses the same frequencies and has a similar intensity).
WP4+WP5:
WP4 had the goal of setting the foundation and of producing the numerical implementation of OQCT in the context of TDDFT. The consortium has now advanced OQCT to a point where predictions can be made for real systems. In particular we are now capable of designing new lasers pulses to enhance particular regions of the high-harmonic spectrum of real molecules. This essentially means that we are capable to engineer the frequency response of real objects. A similar development took place concerning spin-dynamics for both model Hamiltonians developed for quantum dots and for bulk transition metals. Also in this case the results are extremely encouraging, although the high demand of computational resources associated with these methods need to be noted. Also the work in WP4 has to be considered as ground-breaking since control theory has never been applied to time dependent phenomena in real materials before. The major highlights are:
The theory of optimization of the high harmonic generation (HHG) spectrum of atoms and molecules by means of OQCT (in combination with TDDFT for multi-electronic systems) has been successfully established. It has been implemented and tested in the OCTOPUS platform. After establishing the theory and validating the code, we have concentrated on two types of HHG manipulations in order to demonstrate its applicability: (1) selective enhancement of given harmonics, and (2) increase of the HHG plateau.
We have established the theoretical foundations for a OQCT of spin-dynamics, based on electron dynamics modeled with time-dependent density-functional theory (TDDFT). We have demonstrated its feasibility by implementing this theory in the OCTOPUS computational platform. The first example of possible applications obtained consists of ultra-fast single-electron spin manipulation in 2D semiconductor quantum dots with optimally controlled time-dependent electric fields through spin-orbit coupling. A second example is the optimization of an electromagnetic pulse to induce ultrafast demagnetization in Nickel (see WP3+WP5).
We have constructed OQCT for combined electron-ion dynamics, namely we are now in the position to optimize a pulse to produce a desired ionic response. For instance we can design pulses that induce the breaking of a given atomic bond. As first demonstration we have created a pulse able to dissociate the Hydrogen molecule. This is a fundamental advance since it brings a potential design element to elementary photochemistry, since the dynamics of a chemical reaction can be, in principle, controlled. We expect that further development in this area may enable the speed-up of chemical reaction or even the access to reaction, which otherwise would not occur.
Exploitable Foreground
Towards the end of the project, namely in the last six months, the consortium puts a considerable effort in: 1) identifying the possible exploitable foreground developed during the project, 2) investigating a possible strategy for the exploitation of the software produced. These two actions were implemented through two dedicated workshops, namely an Exploitation Strategy Seminar conducted in Dublin by Exploitation Strategy and Innovation Consultant (ESIC), Prof. Špela Stres, and a Cluster Review workshop, which took place in Brussels in conjunction with the other two EU networks on ultrafast dynamics (FEMPTOSPIN and GO FAST). The main findings are:
1) The CRONOS consortium has operated at around TRL3. Although positioning the consortium on the TRL scale was not a requirement of FP7, it gives a metric for the level exploitation expected from the project.
2) It was accepted that developing new advanced methodologies, implementing them in mainstream codes and distribute the codes, is certainly achievable in the three years duration of the project and this was indeed achieved. However, gaining full acceptance by the community to the point that the new methodologies can enter in mainstream materials science requires a much longer outlook. TDDFT was mathematically proved in 1981, the first TDDFT code, Octopus, was released in 2002, and only now the users base has demonstrated a significant pace of growing. Some accelerated speed is expected for the software developed in CRONOS, since it generally sits on mature codes, however the acceptance time has to be expected long (3-5 years outlook).
3) CRONOS developed a significant body of software, mainly advanced TDDFT and OQCT methods. These were implemented in three mainstream codes, namely ELK, Octopus and Smeagol. The three codes are all distributed and supported by a users community of several hundreds research group. In such non-commercial way the software is fully exploited.
4) It was recognized that a full commercial exploitation of the software requires elements, which usually do not have a space in University research (unless investment in that direction is made). These, for instance, include the construction of graphical interfaces, thorough validation and benchmarking and providing customer-oriented professional user-support. It is understood that software firms are possibly better positioned at present to deliver such translational aspect. It is also not clear what is the best license strategy at the moment. GPL or similar are ideal for an academic environment but limits commercial exploitation, although commercial use of GPL software is indeed possible.
5) It is clear that different companies have different requirement from software. These depend on the specific sector, the level of investment in R&D, the vicinity of the industry to market, etc. The requirements go from having plug-and-go tools for designing products directly related to the company core business, to pre-competitive technology evaluation, often to be carried out in collaboration with University researchers, to significant modelling internal R&D activity, to modelling as a service to a company. Given the diversity of such requirements it is not clear at the moment what may be the best strategy for exploitation. The concept of competence centers was articulated as possible way to bring modelling to companies at a pre-competitive stage.
The consortium identified 8 pieces of IP worth exploitation. Five concern software, one is a ground breaking scientific discovery related to a new material, one is a technical instrumentation and one is a product (commercialized by Industry partner Solaronix). The consortium has also established a network of industry contact and it is currently exploring opportunities for collaborative work.
Exploitable results
At the Exploitation Strategy Seminar the consortium identified 8 potentially exploitable results. Five of them are software advances/developments in existing codes, one is a key discovery, one is a new technology for optimal quantum control and one is a product (currently sold). These are listed here with a brief description.
• Exploitable Result 1: The ELK density functional/time dependent density functional theory code - New modules implemented in ELK code: Periodic boundary conditions in TDDFT, non-collinear XC functional (Deliverable D1.1). These two new functionalities allow users to perform time-dependent simulation for periodic solids. The new functional has been designed for describing dynamics in magnetic materials (mostly metals).
• Exploitable Result 2: The Octopus density functional/time dependent density functional theory code. New additions to the Octopus code (deliverables D1.2 D1.3): periodic boundary conditions and module to generate pulses of arbitrary shape. These functionalities allow one to test electromagnetic pulses of custom design shape. It is a fundamental addition for optimal quantum control theory.
• Exploitable Result 3: Module to describe polarisation effects in solar cells (3D). Module developed in the Octopus code to describe the effects of a liquid environment on the optical and electronic properties of materials for solar cells.
• Exploitable Result 4: Spin-transfer torque module in the Smeagol density functional theory and quantum transport code. This module allows the user to calculate spin-transfer torque at finite bias for nanoscale junctions.
• Exploitable Result 5: Modules for optimal quantum control theory in Octopus - Construction of a number of modules for quantum optimal control theory (several deliverables). We generate a range of module to optimize laser pulses in order to produce the desired response of the system.
• Exploitable Result 6: New material for solar energy harvesting - D5.2.1: Determination of the charge transfer dynamics in a supramolecular triad. The material is new (it has been synthesized in CRONOS for the first time). Most importantly it allowed the consortium to understand the fast dynamics of the energy exchange process. The learning can be used for the design of new solar harvesting compounds.
• Exploitable Result 7: New kit for solar energy harvesting modules. The kit (see figure below) was developed by Solaronix and it is currently in the Solaronix catalog for sale.
• Exploitable Result 8: New Hardware for optimal control of ultrafast electron pulse generation. This consists in a new laser setup and associated electronics aimed at generating ultrafast laser pulses.
Moreover, during the course of the CRONOS project, a patent was filed by the partner UPV/EHU, ("Fuente emisora de luz y método de emisión de luz basado en nanotubos de nitruro de Boro", University of the Basque Country, UPV/EHU, PCT/ES2012/070098. ID02462299.).
All the information related to the patent are available at the URL: http://nano-bio.ehu.es/patents.
In conclusion, CRONOS during the three years of its life developed a significant body of IP, mostly related to software, but also with potential in hardware and materials. The consortium has taken several actions towards its exploitation and analyzed in details both the current position and the prospects. In general, the methodological developments from the modeling point of view are already distributed to academia, via the ELK, Octopus and Smeagol code. One product is also currently out for sale from Solaronix.
The consortium also evaluated the barriers towards the penetration of modeling software into a broad industry base. The long times related to the acceptance of the software, together with the diversity in the industry sectors in need for materials modeling (and their diverse requirements) are identified to pose the main challenges.
The two CRONOS Industry partners, Solaronix and CNRS-Spintec, evaluated the consortium potential for exploitation and make a number of recommendations on how computational materials science, and more specific ultra-fast dynamics in real materials, may impact their core business. The industry partners also discussed possible future engagement models for industry and academia.
In general, the two companies found that the work performed by CRONOS was groundbreaking and, although it was basic science in nature, it delivers at a level where companies can start engaging. It was assessed that CRONOS has delivered at around TRL3, which is a position where some companies can confidently work at. Solaronix and CNRS-Spintec then evaluated the readiness of the theoretical development carried out in CRONOS against their core business and projected onto business closely related to their own.
Potential Impact:
CRONOS has made a significant step forward in the modelling of ultrafast phenomena concerning charge and spin dynamics. For the first time time-dependent simulations can be carried out for real materials from first principles, i.e. without depending on experimental data and/or empirical parameterization. At the same time CRONOS was able to tackle the inverse problem, meaning that now electromagnetic pulses can be designed to obtain the desired materials response. This opens a new avenue for materials modelling and at the same time for the design of new materials and processes.
During the running of the project we have achieved fundamental advances in understanding how energy is transferred in organic solar harvesting materials and how the magnetization can be rapidly quenched in magnetic compounds. In the first case we have proved that the energy transfer is coherent in the first few femtosecond of its evolution, meaning that charge and energy oscillate between the donor and the acceptor before the energy is finally transferred. This finding, in which theory and experiments agree well, gives us a new key for designing solar harvesting materials and has far reaching consequences, for instance in biology. At the same time we have discovered how the magnetization is lost in a magnet in the first instant after a laser pulse. In this case we found that spin-orbit interaction is the fundamental force at play. This, together with the formation of spin current, determines the ultrafast dynamics. The consequences of such discovery, again confirmed by experiments, impact the field of magnetic recording, and it is particularly timing since heat-assisted magnetic recording is emerging as the winning technology in the data storage arena. Finally optimal quantum control theory has been implemented, for the first time, together with a full ab initio theory, namely density functional theory. We have then proved that one can now engineer a laser pulse to produce a desired effect. For instance we have demonstrated that an optimize pulse can improve the demagnetization speed of Ni by 40% and can promote the generation of particular optical modes in a high-harmonic generation experiments. The outlook for these methods appears bright as photochemistry by design may become possible. Finally, CRONOS has produced a significant body of software. All the technical implementations of TDDFT and OQCT are now available in the codes Octopus, ELK and Smeagol. These are all well documented and provide a real powerful modelling suit. Most importantly the codes are all distributed for free to the benefit of the large materials modelling community (the combined users of Octopus, ELK and Smeagol are in excess of a thousand). The consortium has also identified a number of possible exploitable results. Most of them concern software, but also hardware development. Furthermore, one of the Industry partners, Solaronix, has designed a new product based on work done in CRONOS. This is a chemical kit for solar cell growth and it is now available for sale at Solaronix web-site.
The consortium IP was monitored with a three-months frequency by the IP and Commercialization Development Office (IPCDO) coordinated by the coordinator at TCD. The office maintained relation with the individual partners Tech Transfer Offices (TTOs) and designed a pipeline of actions to be taken during the duration of the project.
The IPCDO identified early on the specific industry sectors, which could benefit from the research carried on in CRONOS. The industry sectors identified by CRONOS as potential beneficiaries of the scientific developments of the consortium are the following:
1. Chemical manufacturers of solar dyes for solar energy harvesting:
As a direct activity in the CRONOS project, the sector requires to understand and possibly optimise the properties of the dyes.
2. Hard drive manufacturers:
The possible interest is in the area of plasmonic antenna for heat assisted magnetic recording (HAMR). Requirement is to better understand the heating and cooling of ~10nm area of the storage media (to allow the write to occur). Companies include Seagate, Western Digital and Toshiba.
3. Magnetic Random Access Memory (magnetic data storage manufacturers):
The possible interest is in a better understanding of the operations of spin transfer torque. Typically operates in GHz frequency. Some companies in this space include Crocus Technology, Cypress Semiconductor, Everspin.
4. Cancer cell treatment:
This is a very active topic of research. The requirement is to better understand nanoshell photonic interaction. This is a diverse space with several multinational involved: Phillips, Konika-Minolta, Siemens, etc.
5. Optically generating heat, energy sector:
The technology encompasses the use of nanoparticles to absorb optical energy (sunlight). The offer of CRONOS is a better understanding of the interaction of light in terms of absorption and scattering, and conversion to heat (or more perhaps more interesting, steam). Some companies in the SME space appear like a possible customer: Fraunhoffer IGB on water treatment, Holocene Energy.
Dissemination activities performed and significant results
The activities carried out within the framework of the public communication and dissemination have been planned, performed and coordinated by the Project office in collaboration with the Project coordinator, and were carried on with the strong contribution of all the partners. The main objectives achieved during the course of the project have been the following:
• building a distinctive image and style of the Project in order for CRONOS to be easily recognizable.
• The design and maintenance of CRONOS Web site.
• The preparation and distribution of various dissemination materials, such as the official brochure and the project’s posters.
• The spread of information about CRONOS during local and international events.
• Publication of scientific articles.
• Publication of the project press release and external newsletter.
One of the first step performed was building a distinctive image and style of the project in order for CRONOS to be easily recognizable. After the project colours and LOGO have been chosen, the layout of the official documents was designed, together with the one of the presentation to be used during the internal project meetings, and the one for public events. Moreover, starting from the layout of the LOGO, the CRONOS website was designed and used with the aim of giving the possibility to a wide audience to get information about the project’s contents and initiatives.
The web presence was the central element in the dissemination activities of the CRONOS Project during the whole course of the project; therefore the website has been designed to be the primary dynamic information source and to communicate the project main concepts and results. The Project website has been designed during the first 6 months of CRONOS’ lifetime, and it has been launched at the end of November 2012 at the URL: http://www.insrl.eu/project/cronos/.
The key issues that were considered in selecting, structuring and writing content for the CRONOS website are the following:
• to provide a comprehensive description of the work that is being conducted;
• to successfully reach the audiences that may have an interest in CRONOS potential results;
• to facilitate the exchange of documents and information among the Project partners;
• to make the site as transparent as possible, respecting the know-how of the partners that have to be protected.
The website was updated periodically, every three months centrally (by the coordinator), and will be maintained alive for further 5 years. The private area has been developed in a second stage to offer the repository and access point for Project-related information, for use by the Project partners and of the reviewers.
The website could count also on a multimedial libray, where all the videos produced by the partners in the frame of the project, have been uploaded and disseminated http://www.insrl.eu/project/cronos/.
During the course of the project, the consortium has laid the foundations to take part at important public events to promote CRONOS and its results, producing an efficient dissemination kit. In order to be ready to disseminate the Project to external audience, the Project’s the brochure, the flyers and the posters were designed by the Project office and approved by the partners.
The project brochure consists of three sheets of A4 folded, in CRONOS style. The external covering pages accommodate the general Project information and contact details. The internal pages describe the Project’s aims and objectives.
The brochure has been uploaded in a dedicated page in the website, and several copies have been printed and distributed among the partners during the project meeting held in Modena (Italy).
During the whole course of the project, the partners disseminated the project also through posters at the main international conferences in the field. The posters are available in a dedicated page of the project website http://www.insrl.eu/project/cronos/.
The results of the project has been widely disseminated during the whole course of the project. CRONOS was characterized by an impressive number of dissemination actions, in particular publications and presentations of the project’s results at international events attended by the partners. The CRONOS project can count on a very wide list of publications: 135 papers were published during the entire duration of the project, while 10 have been produced and are awaiting for publication. Moreover, the success of the project is demonstrated by the fact that publications were made in highly prestigious journals such as Nature (and associated journals, e.g. Nature Photonics) and Science.
In order to maintain the relationships with the partners press desks and with the external audience, a press desk has been kept alive in a dedicated page of the project website http://www.insrl.eu/project/cronos/.
The Press Desk was managed by TCD, and was responsible for the dissemination through the project’s website of the publication and articles related to the project. Internally, the Press Desk collaborated with the partner to collect periodically the list of dissemination action undertaken by the partners, and to notify the European Commission on them, through the Participant Portal.
Furthermore CRONOS investigators have contributed to over 100 invited talks at international events, and have organized/co-organized about 20 workshops and symposia at conferences. These latter include several training activities for young researchers so that CRONOS scientists have educated about 100 young minds to time-dependent DFT and its capabilities. The general public has also been engaged by CRONOS. The various teams have featured in radio programs and popular press (both regional and international) and the coordinator has presented science to primary schools kids.
In addition a few CRONOS members have received international awards:
1) Christoph Lienau, UOL, Elected as 2013 Fellow of the Optical Society of America, “For outstanding contributions to the field of ultrafast nano-optics, near-field optics and plasmonics.”
2) Stefano Sanvito, TCD, Elected as 2013 Fellow of the Institute of Physics (UK), “For outstanding contributions to materials and devices modelling”.
3) Sarah M. Falke, UOL, 2013 “Green Photonics” Award by Fraunhofer Society, Germany, for an outstanding PhD thesis in the area of photonics.
4) Professor Angel Rubio, UPV/EHU, enters the American Science Academy. 25/04/2015
5) Professor Angel Rubio, UPV/EHU, Awards ceremony Prize Rey Jaime I de Investigación Básica, 25/11/2014
CRONOS’ partners had also a strong record of engagement with the media. The partners have been interviewed by popular press, have given interviews on the radio and have appeared in public lectures broadcasted on Youtube. This activity adds to a significant level of press releases and magazine media coverage, mostly managed by the partners’ own institutions, by CRONOS’ press office and by the press offices of the Nature publishing group. A complete list of CRONOS’ media coverage is available in the project website, and attached to this document.
During the second reporting period, a particular attention was put by the CRONOS consortium, in dissemination activities through the interfacing with other running EU projects, specifically with the two projects funded in the same call of the 7th Framework Programme: NMP.2011.2.1-2 - Modelling of ultrafast dynamics in materials, specifically the GO FAST (GA 280555), and the FEMTOSPIN (GA 103663). The CRONOS project had a leading role in this framework, as organizer of the Cluster Workshop “Theory meets Industry”, which was held the 27th-28th November 2014, in Dublin, and was hosted by the coordinator of the CRONOS project, the Trinity College of Dublin.
Then, as a result of a deep activity done by the three consortia to identify the key exploitable results among the big mole of knowledge generated by the projects themselves, the Cluster Exploitation Workshop of three femtodynamics projects was held on 10th and 11th of March 2015 in Brussels, with the aim of reviewing these projects in view of the industrial exploitation of the newly developed modelling and simulation capabilities. The review was done against the FP7 contract issued by a programme called “Industrial Technologies". However, as pointed out by Dr. Anne de Baas (Project Officer) in her introductory remarks, as FP7 is transitioning to H2020 there is an increasing emphasis by the European Commission on the impact of modelling software and know-how on the global competitiveness of the European industry. This is in accordance with the Roadmap for Materials Modelling as formulated by the European Materials Modelling Council (EMMC). The reviews were thus requested to focus on industrial exploitation potential of the three projects. The workshop foresaw also the participation of Dr. Erich Wimmer, as reviewer of the exploitation potential of the projects, giving the opportunity to the projects of interfacing with an expert on this filed, who gave an important contribution in identifying the exploitability of the projects’ results.
Finally, CRONOS maintained during the whole course of its lifetime, a service of external newsletter. The external newsletter was produced by the coordinator, in collaboration with the Project Office and with the cooperation of the entire consortium, with the aim of disseminating the project’s results and raising public awareness about the potentiality of the CRONOS’ achievements. The contents of the external newsletters were related to the project’s results and activities performed; they included news, “on the spot light” issues and relevant information about the partners. They included also a list of the scientific events organized by the members of the consortium or by the research community. All the issues of the external newsletter are published in the project website, in the press desk page.
List of Websites:
Project website:
http://www.insrl.eu/project/cronos/
Project helpdesk:
info@cronotheory.eu
Coordinator:
Prof. Stefano Sanvito
Professor of Condensed Matter Theory
Director of CRANN
School of Physics, Ph. : +353-1-8963065
Trinity College Dublin, Mob.: +353-87-9595384
Dublin 2, IRELAND Fax.: +353-1-6711759
http://www.spincomp.com
http://www.crann.tcd.ie
CRONOS had one central objective, that of developing a quantitative, flexible and fully atomistic theory of ultrafast dynamics in real materials. This aimed at the creation of the necessary knowledge for advancing two technological areas crucial for the economic future of Europe: new materials for solar energy harvesting and ultra-high density magnetic data storage. In addition, CRONOS looked also at the inverse problem, namely that of engineering an optical excitation designed to produce a desired response (in standard materials science one simply studies how an excitation perturbs a materials system, but does not design specific excitations). This was done through optimal quantum control theory (OQCT).
CRONOS computational method of choice was time-dependent density functional theory, TDDFT, which we had numerically implemented in a number of mainstream codes, namely ELK, Octopus and Smeagol. The workplan was designed to encompass a full idea-to-validation pipeline and thus included: 1) formal methodological development, 2) algorithm implementation, 3) applications to both solar cells and magnetic recording, and 4) experimental validation. Importantly the software developed is distributed freely to the modeling community.
CRONOS has created the foundation of using TDDFT and OQCT to develop a better understanding of ultrafast processes in real materials, in particular related to both charge and spin-dynamics. Most importantly CRONOS has produced a complete development pipeline going from the invention of new theoretical methods, to their implementation in mainstream materials modelling packages (ELK, Octopus and Smeagol), to the use of them in problems related to solar energy harvesting and magnetic data recording, and to their validation in experiments specifically designed to address the ultrafast time scale.
CRONOS output has been published in over 140 research articles, including several in top-tier journals such as Science, Nature Photonics, etc. Furthermore CRONOS investigators have contributed to over 100 invited talks at international events, and have organized/co-organized about 20 workshops and symposia at conferences. These latter include several training activities for young researchers so that CRONOS scientists have educated about 100 young minds to time-dependent DFT and its capabilities. The general public has also been engaged by CRONOS. The various teams have featured in radio programs and popular press (both regional and international) and the coordinator has presented science to primary schools kids. All this was possible thanks to the CRONOS consortium, which comprised the European leaders in the development of ab initio computational techniques and in the production of scientific software for materials science.
CRONOS consortium includes 5 academic institutions, 3 research institutions and 1 SME, based in 7 different countries. CRONOS has been supported by 3,380,058.00€ granted by the EC through 7FP, it was coordinated by Prof. Stefano Sanvito of the Trinity College Dublin (Dublin, Ireland) and carried out by a consortium of 9 leading research institutions.
Project Context and Objectives:
CRONOS’ aim was to develop a quantitative, flexible and fully atomistic theory of ultrafast dynamics in real materials. The effort was devoted to the creation of the necessary knowledge for advancing two technological areas crucial for the economic future of Europe: new materials for solar energy harvesting and ultra-high density magnetic data storage. In addition, CRONOS explored the “inverse problem”. In fact, it did not just look at how an optical excitation perturbs a materials system (either its charge or spins) but also at how such an excitation could be engineered to produce a desired response. As such CRONOS has addressed both the “direct problem”, namely that of calculating the response of materials to perturbations, and the “inverse one”, which consists in designing the perturbations capable of producing the desired response. The theory used for the inverse problem was optimal quantum control theory (OQCT).
The computational method of choice was time-dependent density functional theory, TDDFT, which CRONOS had numerically implemented in a number of mainstream codes, namely ELK, Octopus and Smeagol. The workplan comprised 1) formal methodological development, 2) algorithm implementation, 3) applications to both solar cells and magnetic recording, and 4) experimental validation. Importantly the software developed is distributed freely to the modeling community.
WP1’s objectives were to develop and implement a full suit of technical solutions for TDDFT. These include: 1) the numerical implementation of the time-dependent Kohn-Sham equations with periodic boundary conditions to describe bulk solids in time-dependent external fields; 2) the construction and implementation of advanced meta-GGA functionals and the advanced spin-dependent XC functionals able to describe the non-collinear magnetization dynamics; and 3) the development and implementation of a TDDFT framework for the coupled electron-nuclear dynamics.
WP2’s aimed at applying the method developed in WP1 to the problem of solar energy harvesting. The problems tackled include: 1) the description of the electronic dynamics of charge transfer at interfaces; 2) the identification of both short and long-lived excitations produced by photo-induced electron transfer; 3) the construction of a unified picture of transient phenomena like excitation formation and separation; 4) the identification of the key vibrational and electronic features to optimize self-assembly of molecular components into functionally integrated systems.
The main purpose of WP3 was to establish the foundation of an electronic theory for ultrafast spin-dynamics. In particular we aimed at: 1) constructing an atomistic understanding of ultra-fast spin-dynamics in magnetic transition metals and ferromagnetic materials; 2) exploring the interplay between atomic motion and spin-dynamics in ultra-fast magnetization manipulation; 3) constructing a first step towards a multi-time approach to spin-dynamics including spin-diffusion of conducting electrons. Finally, WP3 investigates the possibility of controlling ultra-fast spin-dynamics by appropriate engineering the shape of laser pulses.
WP4 aimed at translating QOCT to TDDFT, so that to provide a fully quantistic designing tool for materials and processes. This means controlling both the electrons dynamics and also the associated nuclear one. The goal is to achieve control over 1) charge dynamics, 2) spin dynamics, 3) production of high-harmonic generation.
WP5 validated in the lab all the theoretical development achieved, focusing on: 1) the validation of theoretical modelling on solar energy conversion and spin dynamics; 2) the probing of charge and nuclear dynamics at all-organic and organic/inorganic interfaces; 3) the probing of ultrafast spin dynamics in the bulk and at interfaces of ferromagnetic/nonmagnetic film systems; 4) the design of experimental protocols for OQCT.
CRONOS main result is that of having created the foundation of using TDDFT and OQCT to develop a better understanding and control of ultrafast processes in real materials, in particular related to both charge and spin-dynamics. Most importantly CRONOS has produced a complete development pipeline going from the invention of new theoretical methods, to their implementation in mainstream materials modelling packages (ELK, Octopus and Smeagol), to the use of them in problems related to solar energy harvesting and magnetic data recording, and to their validation in experiments specifically designed to address the ultrafast time scale.
WP1 is where most of the formal development took place. On the one hand, we have implemented in both ELK and Octopus a range of tools enabling new calculations, namely periodic boundary conditions for solids and laser pulses of arbitrary intensity and shape. On the other hand, we have invented new exchange and correlation functionals for more accurate calculations of real materials. These include novel meta-GGA for quantum dots and low-dimensional structures and a spin-spiral version of the GGA for magnetic compounds.
WP2 and WP3 focused on applying the suit developed in WP1 respectively to the energy-harvesting problem and to the ultrafast magnetic recording one. These WP were strongly coordinated with the experimental WP5 and the successes of the three must be seen together. In particular, we have produced ground-breaking work demonstrating energy transfer coherence in organic solar cell materials, i.e. we have shown that during the formation of an exciton the charge density and the associated energy oscillate coherently between the donor and the acceptor. Such coherence involves nuclear motion and has been detected experimentally by ultrafast pump-probe experiments. The consequences of this work, published in Science, are reaching far beyond the solar energy arena and may impact also the biology of living being.
When looking at spin-dynamics CRONOS was able to explain the microscopic origin of the first few femtosecond of the laser-induced ultrafast demagnetization process. This consists in the establishment of spin-currents depopulating the region in proximity with the atomic nuclei, followed by a very rapid loss of magnetic moment enabled by spin-orbit interaction. A scaling law relating the spin-orbit strength and the speed of demagnetization was established and proved. Such understanding appears to be universal and can be applied to magnetic materials regardless of their macroscopic order (ferromagnetic, antiferromagnetic or ferromagnetic). Furthermore the optical response of interfaces between magnetic and non-magnetic materials was investigated and a full theory for such interfaces was developed. Also in this case the agreement with experiments is excellent and demonstrates the prediction capabilities of the methods developed.
Finally, the consortium has advanced OQCT in WP4 to a point where now predictions can be made for real systems. In particular, we are now capable of designing new lasers pulses to enhance particular regions of the high-harmonic spectrum of real molecules. This essentially means that we are capable of engineering the frequency response of real objects. A similar development took place concerning spin-dynamics for both model Hamiltonians developed for quantum dots and for bulk transition metals. Also in this case the results are extremely encouraging, although the high demand of computational resources associated with these methods need to be noted.
Overall CRONOS achieved all its targets and goals and has provided a strong development materials platform for the entire materials modelling community. Our implementations are now distributed and the codes are freely accessible.
The results of the project have been widely disseminated during the whole course of the project. CRONOS was characterized by an impressive number of dissemination actions, in particular publications and presentations of the project’s results at international events attended by the partners. The CRONOS project can count on a very wide list of publications: 130 papers were published during the entire duration of the project, while 10 are under review and are awaiting for publication. Moreover, the success of the project is demonstrated by the fact that publications were made in highly prestigious journals such as Nature (and associated journals, e.g. Nature Photonics) and Science.
CRONOS website is available at the URL http://www.insrl.eu/project/cronos/ and it will be kept alive for five years after the end of the project.
Project Results:
The consortium has met all the goals, tasks and deliverables of CRONOS’ original workplan, so that the project has to be considered fully successful. Here we report a summary of CRONOS’ main scientific achievements and then we present the identified exploitable foreground.
Scientific Achievements
CRONOS demonstrated that simulations of ultra-fast dynamics for real materials can be performed and that the results are directly comparable to experiments (typically pump-probe spectroscopy of some kind). Furthermore, some of these simulations have helped our industry partner to produce better materials for solar harvesting devices, so that theory and modelling have been demonstrated to be key elements for the delivery of progress in this space. All this was possible through a workplan encompassing the entire pipeline going from idea to software implementation, to application of the software, to experimental validation of the results. The main scientific achievements are here presented by workpackage and for a detailed description we refer to the relative deliverables.
WP1:
WP1 has constructed a suit of methodological developments aimed at improving the efficiency, accuracy and capability of TDDFT of simulating real materials. In particular it has targeted three main aspects: 1) the possibility of using arbitrary electro-magnetic pulses and of performing simulations for both molecules (open boundary conditions required) and solids (periodic boundary conditions required); 2) the construction of novel exchange and correlation functionals for both non-collinear spin and high accuracy; 3) the formulation and construction of a novel potential surfaces for combined electronic-ionic dynamics. All the developments done in WP1 have been included in the two GPL-distributed codes, Octopus and ELK.
While the implementation of arbitrary EM electro-magnetic pulses and of different boundary conditions have to be considered as technical advances, the development of new exchange and correlation functionals and of a new scheme for electron-ion dynamics have to be considered as major breakthrough.
New non-collinear exchange and correlation (XC) functional (Deliverable 1.4):
We have derived and implemented a spin-non-collinear XC functional for magnetic systems. The derivation was published in Physical Review Letters [F.G. Eich and E.K.U. Gross, Phys. Rev. Lett. 111, 156401 (2013)] while the implementation has been successfully achieved in the ELK electronic structure code. The new XC functional has been shown to improve upon the usual LDA approximation for Cr monolayer. This improvement is due to the XC magnetic field having components that are non-collinear to the local magnetization density. Note that the typical computational overheads of this functional are of the same order of magnitude of the LDA, while more complex functionals having similar qualitative features are significantly more computationally intensive.
Novel scheme for electron-ion dynamics (Deliverable 1.5):
The treatment of nuclear dynamics is indispensable for describing the physical processes underpinning both light-harvesting and ultra-fast spin-dynamics. In both cases, in fact, there is a strong interplay between electronic and ionic degrees of freedom, so that, ideally, one should treat them on the same footing. The “standard” way to take into account classical ionic motion is through the Born-Oppenheimer approximation leading to the classical Ehrenfest forces. However, for the systems investigated in CRONOS the Ehrenfest forces are not sufficiently accurate, and we have investigated whether or not one can find classical forces beyond Ehrenfest that are able to deal with non-adiabatic transitions. Indeed we have shown that this is the case. In particular we have produced three fundamental steps:
1) We have been able to rigorously define and construct classical forces beyond Ehrenfest that are able to deal with non-adiabatic transitions. These emerge from a novel approach to the coupled electron-nuclear dynamics, which is based on an exact factorization of the electron-nuclear wave function. The outcome of this analysis is the definition of a time- dependent potential energy surface (TDPES).
2) The TDPES has been tested against an exactly solvable model, providing clear evidence that the method developed provides an exact alternative description of the nuclear motion.
3) We have developed a novel mixed quantum-classical approach to the coupled electron- nuclear dynamics, which is based on the theory developed in 1) and uses the TDPES tested in 2). Again the method has been tested favorably against an exactly solvable model.
WP2+WP5:
WP2 applies all the formal development done in WP1 to the problem of solar energy harvesting. The general philosophy of WP2 was to conduct, for a number of different solar harvesting compounds, the following computational steps: 1) evaluate accurately the system geometry and exact atomic configuration; 2) evaluate the static energy levels structure; 3) perform time-dependent simulations of the energy transfer process. In addition we have developed a new solvent scheme to be used in combination with TDDFT. This is a quite crucial aspect since typical organic solar harvesting compounds are often in a solution environment. The calculations performed in WP2 were validated by experiments performed in WP5, in particular by means of ultra-fast spectroscopy.
The main highlight of WP2+WP5 concerns the study of the dynamics of both prototypical artificial light harvesting systems and technologically-relevant organic photovoltaic blends. These two works have been published in top tier journals, respectively Nature Communication [“Quantum coherence controls the charge separation in a” Nat. Commun. 4, 1602 (2013)] and Science [“Coherent ultrafast charge transfer in an organic photovoltaic blend” Science 344 1001, (2014)].
Combining high time-resolution femtosecond spectroscopy and time-dependent density functional theory, we have provided compelling evidence that the driving mechanism of the photoinduced current generation cycle is a correlated wavelike motion of electrons and nuclei on the timescale of few tens of femtoseconds. We have highlighted the fundamental role of the interface between chromophore and charge acceptor in triggering the coherent wavelike electron-hole splitting. This result has far reaching impact since it validates a large volume of scattered literature on coherent energy transfer both in the solar energy conversion field and potentially in biology.
WP3+WP5:
WP3 applies all the formal development done in WP1 to the problem of spin dynamics and relaxation in magnetic materials, with impact over the magneto-recording industry. The strategy of the combined program of WP3 and WP5 was to explore spin dynamics in: 1) finite magnetic clusters and bulk solids; 2) in magnets with different magnetic order (ferromagnetic, antiferromagnetic and ferrimagnetic); 3) across interfaces between a magnetic and a non-magnetic metal. Furthermore, since the magnetic order is very sensitive to the lattice structure of the given material, we have investigated the effect of ionic motion on the dynamics. Finally we have provided a first demonstration of optimal quantum control of the demagnetization process in a bulk magnetic material. This all represents ground-breaking work since no dynamics studies at the electronic level have ever been performed before on magnetic system. The key results from WP3+WP5 are the following:
We were able to explain the microscopic processes leading to ultra-fast demagnetization in magnetic metals, with a special focus on the first few femtoseconds of the dynamics (immediately after the exciting laser pulse has extinguished). This consists in the establishment of spin-currents depopulating the region in the proximity of the atomic nuclei, followed by a very rapid loss of magnetic moment enabled by spin-orbit interaction (there is no magnetization loss in absence of spin-orbit coupling). A quadratic scaling law relating the spin-orbit strength and the speed of the demagnetization was established and proved. Such understanding appears to be universal and can be applied to magnetic materials regardless of their macroscopic order (ferromagnetic, antiferromagnetic or ferromagnetic).
The mechanism for ultra-fast demagnetization in heterostructures made of a magnetic and a normal metal, the typical stack in magnetic recording, comprises an additional spin-relaxation channel, namely that originating from the diffusion of spin-polarized currents from the magnetic to the non-magnetic metal. Such ultra-fast mechanism, activate in thin films, has been proved experimentally with pump-probe measurements and modelled theoretically with a multi-scale approach combining TDDFT and quantum transport. The agreement between theory and experiments is excellent.
Finally, we have addressed the question on whether it is possible to exert control of the spin-dynamics by using specifically tailored laser pulses. This controllability is of major importance for future technological applications as it allows the optimization of a particular feature, while incorporating practical constraints. In particular, here we have demonstrated that laser-induced ultrafast demagnetization can be controlled by varying the intensity and frequency of the applied laser. Our work combined the mathematical framework of optimal quantum control theory (OQCT), developed in WP4, with TDDFT. By using OQCT we have optimized a laser pulse that almost doubles the relative loss of total magnetic moment in Ni as compared to a random pulse (that uses the same frequencies and has a similar intensity).
WP4+WP5:
WP4 had the goal of setting the foundation and of producing the numerical implementation of OQCT in the context of TDDFT. The consortium has now advanced OQCT to a point where predictions can be made for real systems. In particular we are now capable of designing new lasers pulses to enhance particular regions of the high-harmonic spectrum of real molecules. This essentially means that we are capable to engineer the frequency response of real objects. A similar development took place concerning spin-dynamics for both model Hamiltonians developed for quantum dots and for bulk transition metals. Also in this case the results are extremely encouraging, although the high demand of computational resources associated with these methods need to be noted. Also the work in WP4 has to be considered as ground-breaking since control theory has never been applied to time dependent phenomena in real materials before. The major highlights are:
The theory of optimization of the high harmonic generation (HHG) spectrum of atoms and molecules by means of OQCT (in combination with TDDFT for multi-electronic systems) has been successfully established. It has been implemented and tested in the OCTOPUS platform. After establishing the theory and validating the code, we have concentrated on two types of HHG manipulations in order to demonstrate its applicability: (1) selective enhancement of given harmonics, and (2) increase of the HHG plateau.
We have established the theoretical foundations for a OQCT of spin-dynamics, based on electron dynamics modeled with time-dependent density-functional theory (TDDFT). We have demonstrated its feasibility by implementing this theory in the OCTOPUS computational platform. The first example of possible applications obtained consists of ultra-fast single-electron spin manipulation in 2D semiconductor quantum dots with optimally controlled time-dependent electric fields through spin-orbit coupling. A second example is the optimization of an electromagnetic pulse to induce ultrafast demagnetization in Nickel (see WP3+WP5).
We have constructed OQCT for combined electron-ion dynamics, namely we are now in the position to optimize a pulse to produce a desired ionic response. For instance we can design pulses that induce the breaking of a given atomic bond. As first demonstration we have created a pulse able to dissociate the Hydrogen molecule. This is a fundamental advance since it brings a potential design element to elementary photochemistry, since the dynamics of a chemical reaction can be, in principle, controlled. We expect that further development in this area may enable the speed-up of chemical reaction or even the access to reaction, which otherwise would not occur.
Exploitable Foreground
Towards the end of the project, namely in the last six months, the consortium puts a considerable effort in: 1) identifying the possible exploitable foreground developed during the project, 2) investigating a possible strategy for the exploitation of the software produced. These two actions were implemented through two dedicated workshops, namely an Exploitation Strategy Seminar conducted in Dublin by Exploitation Strategy and Innovation Consultant (ESIC), Prof. Špela Stres, and a Cluster Review workshop, which took place in Brussels in conjunction with the other two EU networks on ultrafast dynamics (FEMPTOSPIN and GO FAST). The main findings are:
1) The CRONOS consortium has operated at around TRL3. Although positioning the consortium on the TRL scale was not a requirement of FP7, it gives a metric for the level exploitation expected from the project.
2) It was accepted that developing new advanced methodologies, implementing them in mainstream codes and distribute the codes, is certainly achievable in the three years duration of the project and this was indeed achieved. However, gaining full acceptance by the community to the point that the new methodologies can enter in mainstream materials science requires a much longer outlook. TDDFT was mathematically proved in 1981, the first TDDFT code, Octopus, was released in 2002, and only now the users base has demonstrated a significant pace of growing. Some accelerated speed is expected for the software developed in CRONOS, since it generally sits on mature codes, however the acceptance time has to be expected long (3-5 years outlook).
3) CRONOS developed a significant body of software, mainly advanced TDDFT and OQCT methods. These were implemented in three mainstream codes, namely ELK, Octopus and Smeagol. The three codes are all distributed and supported by a users community of several hundreds research group. In such non-commercial way the software is fully exploited.
4) It was recognized that a full commercial exploitation of the software requires elements, which usually do not have a space in University research (unless investment in that direction is made). These, for instance, include the construction of graphical interfaces, thorough validation and benchmarking and providing customer-oriented professional user-support. It is understood that software firms are possibly better positioned at present to deliver such translational aspect. It is also not clear what is the best license strategy at the moment. GPL or similar are ideal for an academic environment but limits commercial exploitation, although commercial use of GPL software is indeed possible.
5) It is clear that different companies have different requirement from software. These depend on the specific sector, the level of investment in R&D, the vicinity of the industry to market, etc. The requirements go from having plug-and-go tools for designing products directly related to the company core business, to pre-competitive technology evaluation, often to be carried out in collaboration with University researchers, to significant modelling internal R&D activity, to modelling as a service to a company. Given the diversity of such requirements it is not clear at the moment what may be the best strategy for exploitation. The concept of competence centers was articulated as possible way to bring modelling to companies at a pre-competitive stage.
The consortium identified 8 pieces of IP worth exploitation. Five concern software, one is a ground breaking scientific discovery related to a new material, one is a technical instrumentation and one is a product (commercialized by Industry partner Solaronix). The consortium has also established a network of industry contact and it is currently exploring opportunities for collaborative work.
Exploitable results
At the Exploitation Strategy Seminar the consortium identified 8 potentially exploitable results. Five of them are software advances/developments in existing codes, one is a key discovery, one is a new technology for optimal quantum control and one is a product (currently sold). These are listed here with a brief description.
• Exploitable Result 1: The ELK density functional/time dependent density functional theory code - New modules implemented in ELK code: Periodic boundary conditions in TDDFT, non-collinear XC functional (Deliverable D1.1). These two new functionalities allow users to perform time-dependent simulation for periodic solids. The new functional has been designed for describing dynamics in magnetic materials (mostly metals).
• Exploitable Result 2: The Octopus density functional/time dependent density functional theory code. New additions to the Octopus code (deliverables D1.2 D1.3): periodic boundary conditions and module to generate pulses of arbitrary shape. These functionalities allow one to test electromagnetic pulses of custom design shape. It is a fundamental addition for optimal quantum control theory.
• Exploitable Result 3: Module to describe polarisation effects in solar cells (3D). Module developed in the Octopus code to describe the effects of a liquid environment on the optical and electronic properties of materials for solar cells.
• Exploitable Result 4: Spin-transfer torque module in the Smeagol density functional theory and quantum transport code. This module allows the user to calculate spin-transfer torque at finite bias for nanoscale junctions.
• Exploitable Result 5: Modules for optimal quantum control theory in Octopus - Construction of a number of modules for quantum optimal control theory (several deliverables). We generate a range of module to optimize laser pulses in order to produce the desired response of the system.
• Exploitable Result 6: New material for solar energy harvesting - D5.2.1: Determination of the charge transfer dynamics in a supramolecular triad. The material is new (it has been synthesized in CRONOS for the first time). Most importantly it allowed the consortium to understand the fast dynamics of the energy exchange process. The learning can be used for the design of new solar harvesting compounds.
• Exploitable Result 7: New kit for solar energy harvesting modules. The kit (see figure below) was developed by Solaronix and it is currently in the Solaronix catalog for sale.
• Exploitable Result 8: New Hardware for optimal control of ultrafast electron pulse generation. This consists in a new laser setup and associated electronics aimed at generating ultrafast laser pulses.
Moreover, during the course of the CRONOS project, a patent was filed by the partner UPV/EHU, ("Fuente emisora de luz y método de emisión de luz basado en nanotubos de nitruro de Boro", University of the Basque Country, UPV/EHU, PCT/ES2012/070098. ID02462299.).
All the information related to the patent are available at the URL: http://nano-bio.ehu.es/patents.
In conclusion, CRONOS during the three years of its life developed a significant body of IP, mostly related to software, but also with potential in hardware and materials. The consortium has taken several actions towards its exploitation and analyzed in details both the current position and the prospects. In general, the methodological developments from the modeling point of view are already distributed to academia, via the ELK, Octopus and Smeagol code. One product is also currently out for sale from Solaronix.
The consortium also evaluated the barriers towards the penetration of modeling software into a broad industry base. The long times related to the acceptance of the software, together with the diversity in the industry sectors in need for materials modeling (and their diverse requirements) are identified to pose the main challenges.
The two CRONOS Industry partners, Solaronix and CNRS-Spintec, evaluated the consortium potential for exploitation and make a number of recommendations on how computational materials science, and more specific ultra-fast dynamics in real materials, may impact their core business. The industry partners also discussed possible future engagement models for industry and academia.
In general, the two companies found that the work performed by CRONOS was groundbreaking and, although it was basic science in nature, it delivers at a level where companies can start engaging. It was assessed that CRONOS has delivered at around TRL3, which is a position where some companies can confidently work at. Solaronix and CNRS-Spintec then evaluated the readiness of the theoretical development carried out in CRONOS against their core business and projected onto business closely related to their own.
Potential Impact:
CRONOS has made a significant step forward in the modelling of ultrafast phenomena concerning charge and spin dynamics. For the first time time-dependent simulations can be carried out for real materials from first principles, i.e. without depending on experimental data and/or empirical parameterization. At the same time CRONOS was able to tackle the inverse problem, meaning that now electromagnetic pulses can be designed to obtain the desired materials response. This opens a new avenue for materials modelling and at the same time for the design of new materials and processes.
During the running of the project we have achieved fundamental advances in understanding how energy is transferred in organic solar harvesting materials and how the magnetization can be rapidly quenched in magnetic compounds. In the first case we have proved that the energy transfer is coherent in the first few femtosecond of its evolution, meaning that charge and energy oscillate between the donor and the acceptor before the energy is finally transferred. This finding, in which theory and experiments agree well, gives us a new key for designing solar harvesting materials and has far reaching consequences, for instance in biology. At the same time we have discovered how the magnetization is lost in a magnet in the first instant after a laser pulse. In this case we found that spin-orbit interaction is the fundamental force at play. This, together with the formation of spin current, determines the ultrafast dynamics. The consequences of such discovery, again confirmed by experiments, impact the field of magnetic recording, and it is particularly timing since heat-assisted magnetic recording is emerging as the winning technology in the data storage arena. Finally optimal quantum control theory has been implemented, for the first time, together with a full ab initio theory, namely density functional theory. We have then proved that one can now engineer a laser pulse to produce a desired effect. For instance we have demonstrated that an optimize pulse can improve the demagnetization speed of Ni by 40% and can promote the generation of particular optical modes in a high-harmonic generation experiments. The outlook for these methods appears bright as photochemistry by design may become possible. Finally, CRONOS has produced a significant body of software. All the technical implementations of TDDFT and OQCT are now available in the codes Octopus, ELK and Smeagol. These are all well documented and provide a real powerful modelling suit. Most importantly the codes are all distributed for free to the benefit of the large materials modelling community (the combined users of Octopus, ELK and Smeagol are in excess of a thousand). The consortium has also identified a number of possible exploitable results. Most of them concern software, but also hardware development. Furthermore, one of the Industry partners, Solaronix, has designed a new product based on work done in CRONOS. This is a chemical kit for solar cell growth and it is now available for sale at Solaronix web-site.
The consortium IP was monitored with a three-months frequency by the IP and Commercialization Development Office (IPCDO) coordinated by the coordinator at TCD. The office maintained relation with the individual partners Tech Transfer Offices (TTOs) and designed a pipeline of actions to be taken during the duration of the project.
The IPCDO identified early on the specific industry sectors, which could benefit from the research carried on in CRONOS. The industry sectors identified by CRONOS as potential beneficiaries of the scientific developments of the consortium are the following:
1. Chemical manufacturers of solar dyes for solar energy harvesting:
As a direct activity in the CRONOS project, the sector requires to understand and possibly optimise the properties of the dyes.
2. Hard drive manufacturers:
The possible interest is in the area of plasmonic antenna for heat assisted magnetic recording (HAMR). Requirement is to better understand the heating and cooling of ~10nm area of the storage media (to allow the write to occur). Companies include Seagate, Western Digital and Toshiba.
3. Magnetic Random Access Memory (magnetic data storage manufacturers):
The possible interest is in a better understanding of the operations of spin transfer torque. Typically operates in GHz frequency. Some companies in this space include Crocus Technology, Cypress Semiconductor, Everspin.
4. Cancer cell treatment:
This is a very active topic of research. The requirement is to better understand nanoshell photonic interaction. This is a diverse space with several multinational involved: Phillips, Konika-Minolta, Siemens, etc.
5. Optically generating heat, energy sector:
The technology encompasses the use of nanoparticles to absorb optical energy (sunlight). The offer of CRONOS is a better understanding of the interaction of light in terms of absorption and scattering, and conversion to heat (or more perhaps more interesting, steam). Some companies in the SME space appear like a possible customer: Fraunhoffer IGB on water treatment, Holocene Energy.
Dissemination activities performed and significant results
The activities carried out within the framework of the public communication and dissemination have been planned, performed and coordinated by the Project office in collaboration with the Project coordinator, and were carried on with the strong contribution of all the partners. The main objectives achieved during the course of the project have been the following:
• building a distinctive image and style of the Project in order for CRONOS to be easily recognizable.
• The design and maintenance of CRONOS Web site.
• The preparation and distribution of various dissemination materials, such as the official brochure and the project’s posters.
• The spread of information about CRONOS during local and international events.
• Publication of scientific articles.
• Publication of the project press release and external newsletter.
One of the first step performed was building a distinctive image and style of the project in order for CRONOS to be easily recognizable. After the project colours and LOGO have been chosen, the layout of the official documents was designed, together with the one of the presentation to be used during the internal project meetings, and the one for public events. Moreover, starting from the layout of the LOGO, the CRONOS website was designed and used with the aim of giving the possibility to a wide audience to get information about the project’s contents and initiatives.
The web presence was the central element in the dissemination activities of the CRONOS Project during the whole course of the project; therefore the website has been designed to be the primary dynamic information source and to communicate the project main concepts and results. The Project website has been designed during the first 6 months of CRONOS’ lifetime, and it has been launched at the end of November 2012 at the URL: http://www.insrl.eu/project/cronos/.
The key issues that were considered in selecting, structuring and writing content for the CRONOS website are the following:
• to provide a comprehensive description of the work that is being conducted;
• to successfully reach the audiences that may have an interest in CRONOS potential results;
• to facilitate the exchange of documents and information among the Project partners;
• to make the site as transparent as possible, respecting the know-how of the partners that have to be protected.
The website was updated periodically, every three months centrally (by the coordinator), and will be maintained alive for further 5 years. The private area has been developed in a second stage to offer the repository and access point for Project-related information, for use by the Project partners and of the reviewers.
The website could count also on a multimedial libray, where all the videos produced by the partners in the frame of the project, have been uploaded and disseminated http://www.insrl.eu/project/cronos/.
During the course of the project, the consortium has laid the foundations to take part at important public events to promote CRONOS and its results, producing an efficient dissemination kit. In order to be ready to disseminate the Project to external audience, the Project’s the brochure, the flyers and the posters were designed by the Project office and approved by the partners.
The project brochure consists of three sheets of A4 folded, in CRONOS style. The external covering pages accommodate the general Project information and contact details. The internal pages describe the Project’s aims and objectives.
The brochure has been uploaded in a dedicated page in the website, and several copies have been printed and distributed among the partners during the project meeting held in Modena (Italy).
During the whole course of the project, the partners disseminated the project also through posters at the main international conferences in the field. The posters are available in a dedicated page of the project website http://www.insrl.eu/project/cronos/.
The results of the project has been widely disseminated during the whole course of the project. CRONOS was characterized by an impressive number of dissemination actions, in particular publications and presentations of the project’s results at international events attended by the partners. The CRONOS project can count on a very wide list of publications: 135 papers were published during the entire duration of the project, while 10 have been produced and are awaiting for publication. Moreover, the success of the project is demonstrated by the fact that publications were made in highly prestigious journals such as Nature (and associated journals, e.g. Nature Photonics) and Science.
In order to maintain the relationships with the partners press desks and with the external audience, a press desk has been kept alive in a dedicated page of the project website http://www.insrl.eu/project/cronos/.
The Press Desk was managed by TCD, and was responsible for the dissemination through the project’s website of the publication and articles related to the project. Internally, the Press Desk collaborated with the partner to collect periodically the list of dissemination action undertaken by the partners, and to notify the European Commission on them, through the Participant Portal.
Furthermore CRONOS investigators have contributed to over 100 invited talks at international events, and have organized/co-organized about 20 workshops and symposia at conferences. These latter include several training activities for young researchers so that CRONOS scientists have educated about 100 young minds to time-dependent DFT and its capabilities. The general public has also been engaged by CRONOS. The various teams have featured in radio programs and popular press (both regional and international) and the coordinator has presented science to primary schools kids.
In addition a few CRONOS members have received international awards:
1) Christoph Lienau, UOL, Elected as 2013 Fellow of the Optical Society of America, “For outstanding contributions to the field of ultrafast nano-optics, near-field optics and plasmonics.”
2) Stefano Sanvito, TCD, Elected as 2013 Fellow of the Institute of Physics (UK), “For outstanding contributions to materials and devices modelling”.
3) Sarah M. Falke, UOL, 2013 “Green Photonics” Award by Fraunhofer Society, Germany, for an outstanding PhD thesis in the area of photonics.
4) Professor Angel Rubio, UPV/EHU, enters the American Science Academy. 25/04/2015
5) Professor Angel Rubio, UPV/EHU, Awards ceremony Prize Rey Jaime I de Investigación Básica, 25/11/2014
CRONOS’ partners had also a strong record of engagement with the media. The partners have been interviewed by popular press, have given interviews on the radio and have appeared in public lectures broadcasted on Youtube. This activity adds to a significant level of press releases and magazine media coverage, mostly managed by the partners’ own institutions, by CRONOS’ press office and by the press offices of the Nature publishing group. A complete list of CRONOS’ media coverage is available in the project website, and attached to this document.
During the second reporting period, a particular attention was put by the CRONOS consortium, in dissemination activities through the interfacing with other running EU projects, specifically with the two projects funded in the same call of the 7th Framework Programme: NMP.2011.2.1-2 - Modelling of ultrafast dynamics in materials, specifically the GO FAST (GA 280555), and the FEMTOSPIN (GA 103663). The CRONOS project had a leading role in this framework, as organizer of the Cluster Workshop “Theory meets Industry”, which was held the 27th-28th November 2014, in Dublin, and was hosted by the coordinator of the CRONOS project, the Trinity College of Dublin.
Then, as a result of a deep activity done by the three consortia to identify the key exploitable results among the big mole of knowledge generated by the projects themselves, the Cluster Exploitation Workshop of three femtodynamics projects was held on 10th and 11th of March 2015 in Brussels, with the aim of reviewing these projects in view of the industrial exploitation of the newly developed modelling and simulation capabilities. The review was done against the FP7 contract issued by a programme called “Industrial Technologies". However, as pointed out by Dr. Anne de Baas (Project Officer) in her introductory remarks, as FP7 is transitioning to H2020 there is an increasing emphasis by the European Commission on the impact of modelling software and know-how on the global competitiveness of the European industry. This is in accordance with the Roadmap for Materials Modelling as formulated by the European Materials Modelling Council (EMMC). The reviews were thus requested to focus on industrial exploitation potential of the three projects. The workshop foresaw also the participation of Dr. Erich Wimmer, as reviewer of the exploitation potential of the projects, giving the opportunity to the projects of interfacing with an expert on this filed, who gave an important contribution in identifying the exploitability of the projects’ results.
Finally, CRONOS maintained during the whole course of its lifetime, a service of external newsletter. The external newsletter was produced by the coordinator, in collaboration with the Project Office and with the cooperation of the entire consortium, with the aim of disseminating the project’s results and raising public awareness about the potentiality of the CRONOS’ achievements. The contents of the external newsletters were related to the project’s results and activities performed; they included news, “on the spot light” issues and relevant information about the partners. They included also a list of the scientific events organized by the members of the consortium or by the research community. All the issues of the external newsletter are published in the project website, in the press desk page.
List of Websites:
Project website:
http://www.insrl.eu/project/cronos/
Project helpdesk:
info@cronotheory.eu
Coordinator:
Prof. Stefano Sanvito
Professor of Condensed Matter Theory
Director of CRANN
School of Physics, Ph. : +353-1-8963065
Trinity College Dublin, Mob.: +353-87-9595384
Dublin 2, IRELAND Fax.: +353-1-6711759
http://www.spincomp.com
http://www.crann.tcd.ie
