In the presentation, a few recent studies of femtosecond excited state dynamics in solution is discussed from a computational perspective.<br/><br/>The parallel development of quantum chemistry and X-ray spectroscopy has allowed us to probe transient species in photochemical processes and to understand the principles governing the reaction dynamics. Experimentally, new X-ray sources give significantly improved spectral resolution and temporal control, but transient X-ray spectroscopy is not easily interpreted and theoretical modelling is an essential complement. Based on multi-configurational quantum chemical calculations, we can reliably simulate X-ray spectra of excited and distorted chemical species. Thereby, we can map the spectral response to electronic and structural changes.<br/><br/>The multi-configurational complete active space - CASPT2 method is an established reference in the study of valence-excited states with an accurate description of chemical bonding, electron relaxation and relativistic effects, such as spin-orbit coupling. The restricted active space - RASPT2 method is an extension, which allows us to target specific high-lying core-excited states and yield a balanced description of valence-excited and core-excited state. Thereby, we can simulate both X-ray absorption spectra and resonant inelastic X-ray scattering for organic and metallo-organic complexes in solution. The relativistic multi-determinant description allows in particular for accurate simulations of L-edge spectra, including the influence of spin-orbit coupling and multiplet effects, of electronically excited transition metal complexes.

Multi-configurational quantum chemical simulations of core-level transitions: Enabling experimental investigations of ultrafast dynamical pathways in photochemical reactions

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.