In this work, we present a time-dependent (TD) selected configuration interaction method based on our recently-introduced adaptive configuration interaction (ACI). We show that ACI, in either its ground or excited state formalisms, is capable of building a compact basis for use in real-time propagation of wave functions for computing electron dynamics. TD-ACI uses an iteratively selected basis of determinants in real-time propagation capable of capturing strong correlation effects in both ground and excited states, all with an accuracy---and associated cost---tunable by the user. We apply TD-ACI to study attosecond-scale migration of charge following ionization in small molecules. We first compute attosecond charge dynamics in a benzene model to benchmark and understand the utility of TD-ACI with respect to an exact solution. Finally, we use TD-ACI to reproduce experimentally determined ultrafast charge migration dynamics in iodoacetylene. TD-ACI is shown to be a valuable benchmark theory for electron dynamics, and it represents an important step towards accurate and affordable time-dependent multireference methods.
@article{arxiv.1909.07810,
title = {Time Dependent Adaptive Configuration Interaction Applied to Attosecond Charge Migration},
author = {Jeffrey B. Schriber and Francesco A. Evangelista},
journal= {arXiv preprint arXiv:1909.07810},
year = {2020}
}