Phase-space wavepacket dynamics of internal conversion via conical intersection: Multi-state quantum Fokker-Planck equation approach

TL;DR

This study uses a multi-state quantum Fokker-Planck equation approach to analyze how conical intersections influence internal conversion processes in photoexcited molecules within condensed phases.

Contribution

It introduces a novel application of the MSQFPE to simulate wavepacket dynamics around conical intersections in a two-dimensional PES model.

Findings

Yields are sensitive to PES profiles near the CI.

Vibrational motion affects non-adiabatic transition probabilities.

The approach distinguishes effects of CI versus avoided crossing models.

Abstract

We theoretically investigate internal conversion processes of a photoexcited molecule in a condensed phase. The molecular system is described by two-dimensional adiabatic ground and excited potential energy surfaces (PESs) that are coupled to heat baths. We study the role of conical intersection (CI) by computing the time evolution of wavepackets for the PESs both with and without the CI. For this purpose, we employ the multi-state quantum Fokker-Planck equation (MSQFPE) for a two-dimensional Wigner space. Numerically integrating the MSQFPE, we investigated the time evolution of wavepackets for the CI and avoided crossing (AC) models. We find that the calculated yields through non-adiabatic transitions are sensitive to the profile of the PESs of the CI model: Due to the vibrational motion in the coupling mode, the yield depends on the distance between the CI point and the minimum point of the adiabatic excited-state PES.