Quantum chemistry solutions for molecules with heavy atoms in realistic environments

This project is aimed at the developments of new quantum chemistry methodology for molecular systems in condensed phases or on interfaces which involve heavy elements and are perturbed by electromagnetic fields.

The computational studies of such systems require methodology which includes the relativistic effects, have a good description of electron correlation and, finally, accounts for the presence of an environment. More advanced quantum chemistry methods which are able to encompass the relativistic and electron correlation effects are computationally very expensive, therefore cannot be used to a molecule and its environment treated as a whole system.

A promising alternative is to use embedding methods, in which the whole system is divided into subsystems: an active molecule of interest and its environment, treated separately by the best (and tailored for them) quantum chemistry models. This project will focus on one such method – the frozen density embedding (FDE). In FDE this partitioning is performed in terms of the electron density and the effect of all other subsystems on the molecule for which the electronic structure and properties are sought is accounted for through the so-called embedding potential. FDE is based on the density functional theory (DFT), nevertheless all the subsystems can either be described with DFT or with wave-function theory (WFT) based methods, what results in various embedding schemes, termed DFT-in-DFT, WFT-in-DFT, WFT-in-WFT. Combined with the relativistic four-component framework, these developments will allow us to revisit and calculate various properties, notably in systems with heavy elements, with the relativistic, correlation and environmental effects calculated from the start.

Project website: https://gosiao.github.io/research/fde