A Vibronic Coupling Model to Study the Nonadiabatic Dynamics of Polyenes

TL;DR

This paper introduces a linear vibronic coupling model for polyenes, applied to trans-hexatriene, to evaluate quantum-classical dynamics methods against quantum simulations, revealing strengths and limitations of surface-hopping and Ehrenfest approaches.

Contribution

The paper develops a vibronic coupling model for polyenes and benchmarks quantum-classical dynamics methods against quantum simulations for the first time.

Findings

Surface-hopping methods are more accurate for short-time dynamics.

None of the methods capture long-time population oscillations.

Surface hopping overestimates internal conversion, Ehrenfest is better near specific parameters.

Abstract

We develop a linear vibronic coupling (LVC) model for polyenes described by the extended Hubbard-Peierls Hamiltonian. This model is applied to trans-hexatriene to benchmark quantum-classical dynamics methods against fully quantum simulations. We find that surface-hopping methods describe short times more accurately than multi-trajectory Ehrenfest. None of the quantum-classical methods studied obtain the long-time population oscillations found in fully quantum simulations. Varying the parameters of the LVC Hamiltonian, we find that surface hopping reproduces the correct trends in the long-time dynamics across a wide range of parameters, but generally overestimates the degree of internal conversion. On the other hand, multi-trajectory Ehrenfest gives more accurate long-time populations in proximity to the hexatriene parameter set.