Periodic Reporting for period 1 - MOFdynamics (Investigating metal-organic frameworks using excited-state dynamics and theoretical spectroscopy)
Reporting period: 2018-09-01 to 2020-08-31
The Marie Sklodowska-Curie Individual Fellowship "MOFdynamics", EU project contract No. 798196, was dedicated to the objective of developing a powerful computational framework for the large-scale description and characterization of spectroscopic properties of solid-state materials. State-of-the-art synthetic approaches enable such a versatile and flexible design of porous materials that the number of hypothetically possible systems is limitless. The immense versatility has led to various application fields of porous materials including for example luminescent sensing, optoelectronics and photocatalysis. Finding the optimal and best-suited material for such applications is challenging as explicit synthesis and experimental characterization of spectroscopic properties are too demanding to explore the huge dimensions of compound space, highlighting the need for computational large-scale screening approaches.
Theoretical and computational approaches therefore have to be designed in such a way that they enable an adequate balance of sufficient accuracy and high efficiency: Aiming for large-scale applications, program packages suitable for high-performance computing have been established and remain a major focus of current research. Furthermore, the development of open-access materials databases and corresponding data management tools have become crucial to advance materials discovery. The CP2K molecular dynamics code is one of the most used electronic-structure codes for high-performance computing worldwide. Being an open source and freely accessible software package, CP2K promotes dissemination of new method developments, enabling easy and rapid adoption by other research groups. The objective of the MOFdynamics project was to extend the tool set of CP2K by developing an efficient and pioneering computational methodology to calculate excited-state properties of solid-state materials. As a second objective, the novel method developments were applied exploiting existing databases for porous materials and investigating the two classes of covalent and metal organic frameworks.
Theoretical and computational approaches therefore have to be designed in such a way that they enable an adequate balance of sufficient accuracy and high efficiency: Aiming for large-scale applications, program packages suitable for high-performance computing have been established and remain a major focus of current research. Furthermore, the development of open-access materials databases and corresponding data management tools have become crucial to advance materials discovery. The CP2K molecular dynamics code is one of the most used electronic-structure codes for high-performance computing worldwide. Being an open source and freely accessible software package, CP2K promotes dissemination of new method developments, enabling easy and rapid adoption by other research groups. The objective of the MOFdynamics project was to extend the tool set of CP2K by developing an efficient and pioneering computational methodology to calculate excited-state properties of solid-state materials. As a second objective, the novel method developments were applied exploiting existing databases for porous materials and investigating the two classes of covalent and metal organic frameworks.
The main achievement of the MOFdynamics project was the implementation of the proposed highly efficient and flexible computational framework for the description and characterization of spectroscopic properties of porous framework materials. The accomplished method developments are part of the freely available CP2K program package, including features to enhance the efficiency of the time-dependent density functional theory code, to simulate electronic spectra using semi-empirical tight binding or density functional theory and to allow for geometrical changes of the excited state providing fluorescence spectra.
More precisely, semi-empirical tight-binding approaches, which represent the state-of-the-art of competing molecular electronic structure codes, were implemented in CP2K and extended to treat periodic boundary conditions, paving the way for an efficient structural (pre-)optimization and excited-state treatment of extended systems, a crucial bottleneck of so far existing large-scale screening protocols. The tool set of semi-empirical algorithms was complemented by furthermore developing highly efficient time-dependent density functional theory approaches featuring hybrid functionals. Hybrid functionals include the effect of exact exchange which is crucial for an accurate description of spectroscopic properties, however they are computationally demanding and therefore often a major obstacle for large-scale applications. Exploiting auxiliary density matrix and local density fitting approaches, the efficiency of existing hybrid functional implementations could be drastically improved.
Further main achievements were the implementation of excited-state nuclear forces for the described semi-empirical and time-dependent density functional theory approaches representing the first step toward an efficient computational framework for molecular dynamic simulations. The general adaptive setup of the various novel features within the CP2K program code redefines state-of-the-art boundaries for the characterization of porous materials reducing computational timings by orders of magnitude and therefore fostering the role of theoretical chemistry in materials design.
The research was presented at numerous scientific conferences and corresponding program code was and will be made available as part of the official CP2K releases.
More precisely, semi-empirical tight-binding approaches, which represent the state-of-the-art of competing molecular electronic structure codes, were implemented in CP2K and extended to treat periodic boundary conditions, paving the way for an efficient structural (pre-)optimization and excited-state treatment of extended systems, a crucial bottleneck of so far existing large-scale screening protocols. The tool set of semi-empirical algorithms was complemented by furthermore developing highly efficient time-dependent density functional theory approaches featuring hybrid functionals. Hybrid functionals include the effect of exact exchange which is crucial for an accurate description of spectroscopic properties, however they are computationally demanding and therefore often a major obstacle for large-scale applications. Exploiting auxiliary density matrix and local density fitting approaches, the efficiency of existing hybrid functional implementations could be drastically improved.
Further main achievements were the implementation of excited-state nuclear forces for the described semi-empirical and time-dependent density functional theory approaches representing the first step toward an efficient computational framework for molecular dynamic simulations. The general adaptive setup of the various novel features within the CP2K program code redefines state-of-the-art boundaries for the characterization of porous materials reducing computational timings by orders of magnitude and therefore fostering the role of theoretical chemistry in materials design.
The research was presented at numerous scientific conferences and corresponding program code was and will be made available as part of the official CP2K releases.
The MOFdynamics project makes a significant contribution to advance computational approaches for state-of-the-art research within the multidisciplinary field of quantum chemistry, solid-state physics and materials science. The accomplished method developments represent pioneering work, promoting a computational tool set which comprises various semi-empirical and time-dependent density functional theory methods for the treatment of excited states and related spectroscopic properties, paving the way toward a comprehensive electronic structure modeling of extended materials. Being incorporated in the CP2K program package, the methodologies are suitable for large-scale applications exploiting advanced computational and technical procedures for high-performance computing. Furthermore, being freely accessible as an open-source code, the conducted research will be of benefit to the broad scientific community worldwide, advancing the role of computational chemistry in the discovery of novel materials and representing a significant added value to the community and European excellence.