Making peace with random phases: Ab initio conical intersection dynamics in random gauges

TL;DR

This paper introduces a novel random-gauge local diabatic representation enabling accurate ab initio modeling of conical intersection dynamics directly from adiabatic states with random phases, facilitating integration of electronic structure calculations into non-adiabatic quantum dynamics.

Contribution

It develops a new method to handle random phases in adiabatic states, allowing exact conical intersection dynamics modeling from electronic structure data.

Findings

Successfully modeled conical intersection dynamics in the Shin-Metiu model

Demonstrated the method's effectiveness with and without external magnetic fields

Provided a pathway for ab initio nonadiabatic quantum dynamics simulations

Abstract

Ab initio modeling of conical intersection dynamics is crucial for various photochemical, photophysical, and biological processes. However, adiabatic electronic states obtained from electronic structure computations involve random phases, or more generally, random gauge fixings, which hampers the modeling of nonadiabatic molecular dynamics. Here we develop a random-gauge local diabatic representation that allows an exact modeling of conical intersection dynamics directly using the adiabatic electronic states with phases randomly assigned during the electronic structure computations. Its utility is demonstrated by an exact ab initio modeling of the two-dimensional Shin-Metiu model with and without an external magnetic field. Our results provide a simple approach to integrating the electronic structure computations into non-adiabatic quantum dynamics, thus paving the way for ab initio modeling of conical intersection dynamics.