Reduced hierarchy equations of motion approach with Drude plus Brownian spectral distribution: Probing electron transfer processes by means of two- dimensionalcorrelation spectroscopy

TL;DR

This paper develops an advanced theoretical method to analyze electron transfer processes in complex environments using two-dimensional correlation spectroscopy, incorporating both overdamped and underdamped modes for more accurate modeling.

Contribution

It extends the reduced hierarchy equations of motion to include Drude and Brownian spectral distributions, enabling detailed simulation of electron transfer and vibrational effects in 2D spectra.

Findings

Successfully models ET processes with characteristic peaks in 2D spectra.

Demonstrates decay of echo signals related to ET dynamics.

Captures system-bath coherence effects under external perturbations.

Abstract

We theoretically investigate an electron transfer (ET) process in a dissipative environment by means of two-dimensional (2D) correlation spectroscopy. We extend the reduced hierarchy equations of motion approach to include both overdamped Drude and underdamped Brownian modes. While the overdamped mode describes the inhomogeneity of a system in the slow modulation limit, the underdamped mode expresses the primary vibrational mode coupled with the electronic states. We outline a procedure for calculating 2D correlation spectrum that incorporates the ET processes. The present approach has the capability of dealing with system-bath coherence under an external perturbation, which is important to calculate nonlinear response functions for non-Markovian noise. The calculated 2D spectrum exhibits the effects of the ET processes through the presence of ET transition peaks along the $\Omega_1$ axis, as well as the decay of echo signals.