QM/MM Modeling of Vibrational Polariton Induced Energy Transfer and Chemical Dynamics

TL;DR

This paper introduces a hybrid QM/MM CavMD simulation method to model vibrational polariton effects on chemical dynamics, enabling efficient analysis of energy transfer and reaction pathways under vibrational strong coupling in dilute solutions.

Contribution

The paper develops a linear-scaling QM/MM CavMD approach for modeling VSC effects, allowing detailed simulation of polariton-induced energy transfer and chemical reactions in large systems.

Findings

Polariton dephasing to dark modes observed in simulations

Selective excitation of equatorial CO vibrations predicted

Cavity influences on Fe(CO)$_5$ pseudorotation dynamics demonstrated

Abstract

Vibrational strong coupling (VSC) provides a novel means to modify chemical reactions and energy transfer pathways. To efficiently model chemical dynamics under VSC in the collective regime, herein a hybrid quantum mechanical/molecular mechanical (QM/MM) cavity molecular dynamics (CavMD) scheme is developed and applied to an experimentally studied chemical system. This approach can achieve linear scaling with respect to the number of molecules for a dilute solution under VSC by assuming that each QM solute molecule is surrounded by an independent MM solvent bath. Application of this approach to a dilute solution of Fe(CO)$_5$ in n-dodecane under VSC demonstrates polariton dephasing to the dark modes and polariton-enhanced molecular nonlinear absorption. These simulations predict that strongly exciting the lower polariton may provide an energy transfer pathway that selectively excites the equatorial CO vibrations rather than the axial CO vibrations. Moreover, these simulations also directly probe the cavity effect on the dynamics of the Fe(CO)$_5$ Berry pseudorotation reaction for comparison to recent two-dimensional infrared spectroscopy experiments. This theoretical approach is applicable to a wide range of other polaritonic systems and provides a tool for exploring the use of VSC for selective infrared photochemistry.