Theoretical methods for the study of excited systems in quantum chemistry are important for understanding processes driven by photoabsorption, such as formation of the aromatic precursors to soot and light-harvesting in photosynthetic bacteria. These methods however remain limited by both accuracy and speed of the electronic excited-state calculations. This is particularly the case for higher order excitations where strong orbital relaxations and multi-reference character hinder conventional modelling methods. While Davidson-corrected multireference configuration interaction (MRCI+Q) calculations are in general very reliable in these situations, the method scales steeply with system size. By leveraging recent advances in uniting excited state variational Monte Carlo and selective configuration interaction approaches, in further combination with diffusion Monte Carlo, we explore the ability of these methods to accurately treat challenging multi-electron excitations in molecules beyond the reach of traditional MRCI.

Treating multi-electron excitations with a QMC-based approach

2019 Fall National Meeting

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