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Correlated Multielectron Dynamics in Intense Light Fields

Final Report Summary - CORINF (Correlated Multielectron Dynamics in Intense Light Fields)


The CORINF network was designed to provide researchers in the early stages of their careers multidisciplinary training and research in the fields of physics of intense light-matter interactions and attosecond science. The network included eleven nodes from UK, Germany, France, Italy and Spain, and offered training for twelve early stage researchers and two experienced researchers.
The scientific focus of the research programme is the development of theoretical foundations for angstrom-scale spatial resolution imaging of multi-electron dynamics in atoms, molecules and clusters, with a fine temporal resolution ranging from femtoseconds down to attoseconds.

The main research and training objectives of the CORINF project were to: (1) provide an ideal multidisciplinary environment for training young researchers in the combination of physics, chemistry and computational methods, (2) foster synergies of different areas in atomic and molecular physics, quantum chemistry, and software development, (3) develop theoretical methods describing multi-electron dynamics in atoms, molecules and clusters in intense laser fields, (4) lay the theoretical foundation for imaging structures and multi-electron dynamics in molecules and clusters at the corresponding spatial and temporal scales, (5) develop a flexible numerical platform for modelling intense-field multi-electron dynamics, and (6) deliver the forefront technology in the form of a set of advanced numerical tools and software.

To facilitate the achievement of the mentioned scientific objectives, the CORINF programme has been divided into three work packages. Work package 1 focuses on imaging electron-hole dynamics and coupled electron-nuclear dynamics in molecules. Research in the previous module feeds into work package 2, which addresses multi-electron dynamics, and energy absorption in molecules and clusters irradiated with IR and XUV laser fields. Work package 3 is the research and development component of the project, aiming to develop a set of numerical tools for the interaction of atoms, molecules and clusters with intense laser fields.


To achieve the training goals of the network, each CORINF node created at the local level a comprehensive and well-structured environment providing early stage researchers wide training opportunities in attosecond science. Within their doctoral schools, the fellows were also offered the possibility to attend very advanced postgraduate courses in physics, chemistry and computational sciences. In addition, the fellows had one or two secondments, away from their home institution, at different nodes, with the aim to strengthen their ties with other project partners and benefit from the expertise of their colleagues at different institutions. Furthermore, to complement their training, the network organised three research schools. A summer school in June 2012 offered intensive training on all aspects of ultrafast and strong field physics, with lectures and tutorials given by experts in this research field. A second school was organised in May 2013 with an emphasis on strong-field ionisation and high harmonic generation in atoms and molecules. Another school was organised by the fellows themselves at the end of April 2014, and focused on both further scientific training, and also on career choices with soft-skill modules, featuring eminent speakers from the academic and business communities.

The resulting expertise of the fellows has been reflected in the high quality of their research, as shown by their publications in first-tier journals. In addition, several fellows have been invited to give talks in different national and international workshops and conferences. The last network meeting organised in March 2015 in the UK, where the fellows were invited to summarise their work, clearly demonstrated the quality of the training they received in these last four years. The fellows not only conducted their research projects very well, but also learned different theoretical methods and mastered several numerical techniques used in attosecond physics.


To achieve the research goals of the programme, efficient collaborations between the different network nodes have been developed. Additionally, knowledge exchange between CORINF principal investigators and fellows has been fostered by the organisation of eight network meeting at or near partner locations, with the final meeting organised in March 2015 in Chicheley Hall (UK), where the PIs and the fellows summarised their scientific findings. The research outcome largely exceeded the envisaged goals of each individual project. All the milestones and deliverables have been achieved. The scientific results of the network have been published in 117 papers in very high quality journals, and several other papers are in press or in preparation. The main scientific results of the network have been presented by both the fellows and their supervisors at various scientific meetings.

Several research projects have been successfully carried out within the CORINF network, and the scientific outcome of the programme is too large to be addressed here in detail. Therefore, we present a number of research highlights reflecting the high quality of the work performed within this network, and also the strong collaborations that have developed between the different nodes.

- Imperial team developed a fully ab-initio numerical package, based on the ADC-Stieltjes-Lanczos many-body theory, to resolve and image attosecond to femtosecond multielectron dynamics in polyatomic molecules, achieving the most ambitious goal of the network. The code is currently prepared for open access, open source software package.
- UniTS and HUM developed a DFT LCAO B-spline code for the description of strong field ionisation and HHG in complex polyatomic molecules, achieving another highly ambitious goal of the network.
- In a collaboration between Imperial and UniTS, the ADC method has been implemented in the B-spline single-electron basis, and applied it to the calculation of photoionization cross-sections, and high-order harmonic generation (HHG) spectra in polyatomic molecules.
- Researchers at Imperial developed a practical scheme for generating isolated elliptically polarized attosecond pulses using bichromatic counter rotating circularly polarized laser fields.
- Imperial demonstrated that electronic coherence, created on the attosecond time scale at the start of a photoreaction, can influence nuclear dynamics many femtoseconds later.
- Imperial and UAM developed a semiclassical analytical model to image coupled electronic-nuclear motion during dissociative autoionisation initiated by an attosecond pulse.
- In a collaboration between MBI, UAM and Imperial, researchers demonstrated the possibility to control quantum dynamics at conical intersections at the sub-femtosecond time scale.
- MBI, UAM and Imperial, demonstrated the possibility to use high harmonic generation (HHG) spectroscopy to probe coupled electronic-nuclear dynamics, and to time-resolve electron localisation following dissociative ionisation of H2 molecules.
- MBI developed an analytical R-matrix theory for strong field ionisation.
- MBI developed the new concept of the Larmor clock, and used it to address fundamental issues in attosecond spectroscopy.
- In a collaboration between MBI, Imperial and LMU, researchers used analytical and numerical methods to demonstrate that tunnelling, in strong field ionisation, takes no time.
- In a collaboration between MBI and QUM, the applicability of the UK R-matrix code has been extended to the study of photoionisation by strong static electric fields.
- MBI demonstrated that HHG can enhance weak chiral signals by orders of magnitude allowing to monitor chiroptical interactions with sub-femtosecond temporal resolution.
- Researchers at PAR demonstrated that a tomographic image of valence molecular orbitals can be reconstructed from energy resolved photoelectron spectra, in a similar way to HHG spectroscopy.
- The PAR node developed a numerical code for the complete description of the excitation, relaxation, and decoherence dynamics of ensembles of coupled atomic or molecular systems, taking into account collective effects and dephasing.
- In a collaboration between UniTS and UAM, researchers observed that ionization of amino acids by an isolated attosecond pulse leads to ultrafast charge dynamics on a sub-femtosecond temporal scale, shorter than the vibrational response of the molecule. Their results were confirmed by experimental observations.
- HUM developed a new concept of a quantum simulator for attosecond physics based on ultracold atoms in an optical trap.
- LMU developed a software package named “time-dependent recursive indexing” (tRecX), integrating two mathematical methods: “infinite range Exterior Complex Scaling” (irECS), providing perfect absorbing boundary conditions at very low numerical cost, and the time-dependent surface flux (tSURFF) method for computing single- and double-photo-emission spectra.
- QUB developed a time-dependent R-matrix theory and implemented it in a numerical code to study single and double ionisation in strong IR and XUV fields.
- At the TOUL node, researchers developed a stochastic extension of mean field theory, complemented by a quantum relaxation strategy, in order to study the response of clusters and macromolecules to intense laser fields.
- Researchers at TOUL developed a real time TDDFT open source code (teleman).
- MPG has been able to elucidate the mechanism behind the recently discovered large photoelectron peak at low excess energy (the so called LES).
- Researchers at MPG discovered that in clusters subject to short intense X-ray pulses, massively parallel ionisation can occur, where many X-ray photons produce an equal number of photo-electrons or Auger electrons.
- The recent highlight of the MPG project is the finding that in violent X-ray absorption by large molecules and clusters, the abundantly existing protons are beneficial to tame radiation damage: they carry away energy (deposited by the photons) and charge (to balance the loss through photo-electrons). This may have important implications not only for imaging molecules with sub-Å and 1-fsec resolutions, but also for understanding radiation damage from very intense X-ray sources.

Regarding the R&D component of the CORINF network, several numerical codes have been developed at different nodes. Some of them are already available through collaborations with the corresponding developers, and others have been made freely available to the scientific community.
- Imperial developed a fully ab-initio software package to resolve and image attosecond to femtosecond multielectron dynamics in polyatomic molecules. The code is currently prepared for open access.
- The DFT LCAO B-spline code for strong field ionisation and HHG is available to the scientific community through collaboration with the UniTS node.
- The time-dependent R-matrix code for strong IR and XUV fields is available to the scientific community through collaboration with the QUB node.
- The PAR node developed a series of simple codes to deal with (1) dynamics of 1 electron in a strong laser field (in 1 dimension), (2) dynamics of 2 electrons in a strong field (in 2D), and (3) dynamics of 2 electrons and a single internuclear degree of freedom in a strong field (3D). The codes are available through collaboration with the corresponding node.
- A numerical code for semiclassical ionisation rates of aligned molecules has been developed by Imperial. The corresponding open source software package, PyMolion, is available for download from: .
- QUM and MBI developed a numerical code for calculating total and angle-resolved photo-ionisation cross sections. It is distributed as a freeware via the UK CCPForge program depositary.
- A real time TDDFT code (teleman) has been developed by the TOUL node (and their collaborators), with highly sophisticated tools for the analysis of photoemission. The first version of the code is accessible (freeware) at: .
- LMU developed the the tRecX code, which is a user-friendly universal Schrödinger and Maxwell solver. It can be found at: .


In the course of the CORINF project, different theoretical methods and numerical techniques have been developed to study the interaction of atoms, molecules and clusters with strong laser fields. Several numerical codes have been released and made freely available to the broad scientific community for further investigations of attosecond and femtosecond processes. The research outcome of the network exceeded the planned goals, and all the milestones and deliverables have been achieved. Significant steps in our understanding of the dynamical response of quantum systems, ranging from atoms to macromolecules, irradiated by intense laser fields, have been made. Research activities carried out within the network clearly contributed to push the frontiers of attosecond science. The success of the CORINF project is the product of effective training of the fellows and strong collaborations between the different nodes.