On the influence of the "donor"/"acceptor" presence on the excitation states in molecular chains: non-adiabatic polaron approach

TL;DR

This paper investigates how the presence of a donor or acceptor molecule affects excitation states in molecular chains, revealing that the chain influences the donor's excitation energy levels and migration, with implications for energy transfer processes.

Contribution

It introduces a non-adiabatic polaron model to analyze excitation migration in molecular chains with donor/acceptor molecules, highlighting the chain's influence on energy levels and transfer conditions.

Findings

The excitation forms a non-adiabatic polaron state.

The donor molecule's properties are minimally affected by the chain.

The chain can shift the energy level of the donor excitation.

Abstract

In the paper, we considered a molecular structure that consists of a molecular chain and an additional molecule ("donor"/"acceptor") that can inject (or remove) single excitation (vibron, electron, e.t.c.) onto the molecular chain. We assumed that the excitation forms a self-trapped state due to the interaction with mechanical oscillations of chain structure elements. We analyzed the energy spectra of the excitation and showed that its state (when it migrates to the molecular chain) has the properties of the non-adiabatic polaron state. The conditions under which the excitation can migrate from one subsystem to another were considered. It was shown that the presence of a "donor" molecule cannot significantly change the properties of the excitation located on the molecular chain. At the same time, the molecular chain can affect the position of the energy level of the excitation localized on the "donor" subsystem. Indirectly, this can influence the process of excitation migration from one subsystem to another one. The influence of basic energy parameters of the system and the environment temperature on this process are discussed. The entire system was assumed to be in thermal equilibrium with the environment.