<i>Ab Initio</i> Polariton Transport Dynamics with the Classical Path Approximation.

Abstract

We present an <i>ab initio</i> framework for simulating polariton transport dynamics based on the classical path approximation (CPA). The quantum dynamics of polariton transport involves simulating many electronic degrees of freedom, making a fully <i>ab initio</i> dynamics simulation computationally expensive. We demonstrate that the CPA, which removes the need for excited-state nuclear gradients, is well-suited for polaritonic systems because collective light-matter coupling leads to vanishing excited-state forces. Benchmark comparisons between CPA and full evaluation of the excited-state forces show excellent agreement for polariton transport results in model light-matter systems such as polariton group velocities and mean-squared displacements. <i>Ab initio</i> simulations of polariton transport using CPA reproduce key physical trends that are observed in experiments with BODIPY molecules. Our work establishes the CPA as a highly efficient tool for <i>ab initio</i> investigations of transport and energy flow in hybrid light-matter systems.