Development of efficient means to describe dynamic electron correlation effects in strongly correlated molecular systems

• Applicant: Professor Dr. Michael Roemelt
• Subject Area: Theoretical Chemistry: Molecules, Materials, Surfaces ; Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544887640

This project aims at the development of multireference electronic structure methods that provide access to accurate and reliable electronic energies and structures for molecular systems with many strongly correlated electrons. In the first part of the enivsaged work, a partially uncontracted reformulation of the well-established N-electron valence state perturbation theory will be developed and implemented. Through usage of the heatbath CI-rationale that has been succesfully applied in the context of selected configuration interaction (SCI) methods, the computational cost of the proposed will be reduced while an efficient implementation will allow for favorable parallelization properties. The second part of this project encompasses the development and implementation of the recently introduced adiabatic connection approach to calculate dynamic electron correlation effects on top of selected CI reference wavefunctions. With a working implementation at hand, the method will be extended to compute nuclear gradients at the same level of theory. Importantly, the proposed developments will result in openly available computer codes that allow for the investigation of molecular systems with many strongly correlated electrons on a physically sound basis. A set of initial test calculations on chemically relevant compounds will demonstrate the capabilities and limitations of the developed programs.

• DFG Programme: Research Grants