Molecular Origin of Correlated Bath Effects in Photoinduced Charge Transfer Dynamics in Polar Solvents

Nonadiabatic dynamics in the condensed phase often involve correlated environments shared by multiple electronic states, challenging the traditional isolated bath assumption. We investigate these effects using the multistate harmonic (MSH) model and atomistic Hamiltonian applied to photoinduced charge transfer in a trimer consisting of a methylperylene donor and two tetracyanoethylene acceptors dissolved in a polar solvent. We propose a geometric metric based on the angular relationship of reorganization energies between transitions sharing an initial state to quantify bath correlation. Our analysis identifies distinct regimes: a correlated bath where synchronized energy gap fluctuations facilitate competing reactions, and an anticorrelated bath where fluctuations favoring one reaction suppress the other. These energetic correlations are modulated by molecular conformation and charge distribution, specifically through changes in dipole moments and solvent-accessible surface area. This study provides a connection between the energetic perspective of environmental correlations and the molecular details governing nonadiabatic dynamics in polar solvents.