Excited-state Forces within a First-principles Green's Function Formalism

TL;DR

This paper introduces a novel first-principles Green's function formalism to accurately compute forces in optically excited states, enabling detailed studies of molecular relaxation, dynamics, and photoluminescence.

Contribution

It develops a new method combining GW and Bethe Salpeter Equation to efficiently calculate excited-state forces from first principles.

Findings

Accurately predicts excitation energies of molecules.

Describes photoinduced structural deformations.

Enables simulation of excited-state molecular dynamics.

Abstract

We present a new first-principles formalism for calculating forces for optically excited electronic states using the interacting Green's function approach with the GW-Bethe Salpeter Equation method. This advance allows for efficient computation of gradients of the excited-state Born-Oppenheimer energy, allowing for the study of relaxation, molecular dynamics, and photoluminescence of excited states. The approach is tested on photoexcited carbon dioxide and ammonia molecules, and the calculations accurately describe the excitation energies and photoinduced structural deformations.