Semiclassical Nonadiabatic Molecular Dynamics Using Linearized Pair-Density Functional Theory

TL;DR

This paper introduces a new semiclassical nonadiabatic molecular dynamics method using linearized pair-density functional theory (L-PDFT), which offers accurate potential energy surfaces at reduced computational cost, enabling efficient simulations of photoisomerization.

Contribution

The study integrates L-PDFT with SHARC and PySCF to perform nonadiabatic dynamics, demonstrating its effectiveness in simulating photoisomerization with accuracy comparable to more expensive methods.

Findings

L-PDFT successfully simulates photoisomerization of cis-azomethane.

L-PDFT yields results similar to extended multi-state CASSCF/second-order perturbation theory.

The method shows promise for broader photodynamics applications.

Abstract

Nonadiabatic molecular dynamics is an effective method for modeling nonradiative decay in electronically excited molecules. Its accuracy depends strongly on the quality of the potential energy surfaces, and its affordability for long direct-dynamic simulations with adequate ensemble averaging depends strongly on the cost of the required electronic structure calculations. Linearized pair-density functional theory (L-PDFT) is a recently developed post-self-consistent field multireference method that can model potential energy surfaces with an accuracy similar to expensive multireference perturbation theories but at a computational cost similar to the underlying multiconfiguration self-consistent field method. Here we integrate the SHARC dynamics and PySCF electronic structure code to utilize L-PDFT for electronically nonadiabatic calculations and use the combined programs to study the photoisomerization reaction of cis-azomethane. We show that L-PDFT is able to successfully simulate the photoisomerization and yields results similar to the more expensive extended multi-state complete active space second-order perturbation theory. This shows that L-PDFT can model internal conversion, and it demonstrates its promise for broader photodynamics applications.