Time Dependent Adaptive Configuration Interaction Applied to Attosecond Charge Migration

TL;DR

This paper introduces a time-dependent adaptive configuration interaction (TD-ACI) method for simulating ultrafast electron dynamics, demonstrating its effectiveness in modeling attosecond charge migration in molecules.

Contribution

The work develops a novel TD-ACI approach that efficiently captures strong correlation effects in real-time electron dynamics simulations, with tunable accuracy and cost.

Findings

Successfully benchmarked against exact solutions in benzene models.

Reproduced experimental ultrafast charge migration in iodoacetylene.

Demonstrated TD-ACI as a valuable tool for electron dynamics studies.

Abstract

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.