The influence of interchain coupling on intramolecular oscillation mobility in coupled macromolecular chains: the case of coplanar parallel chains

TL;DR

This paper investigates how interchain coupling affects intramolecular oscillation mobility in coupled macromolecular chains, revealing a transition from free to immobile excitons near physiological temperatures, with implications for biological and polymer systems.

Contribution

It extends the Holstein polaron model to two coupled chains, analyzing exciton band splitting and mobility changes due to interchain interactions and temperature effects.

Findings

Interchain coupling causes exciton band splitting.

Temperature influences exciton mobility, causing a transition from free to heavy quasiparticles.

Results applicable to DNA and polymer film exciton transport.

Abstract

We enlarge our results from the study of the hopping mechanism of the oscillation excitation transport in 1D model of one biology-like macromolecular chain to the case of a system composed from two 1D parallel macromolecular chains with consideration of the properties of intramolecular oscillation excitations. We suppose, that due to the exciton interaction with thermal oscillation (generated by mechanical phonon subsystem) of structural elements (consisting of the peptide group) of the chains, the exciton becomes by self trapped and forms the polaron state. We suggest a model which generalizes the modified Holstein polaron model to the case of two macromolecular chains and find that because of the interchain coupling, the exciton energy band is splitted into two subbands. The hopping process of exciton migration along the macromolecular chains is studied in dependence of system parameters and temperature. We pay an special attention to the temperature range (near T=300 K) in which living cells operate. It is found that for the certain values of the system parameters there exists the abrupt change of the exciton migration nature from practically free (light) exciton motion to an immobile (heavy, dressed by phonon cloud) quasiparticle We discuss an application of the obtained results to the exciton transport both within deoxyribonucleic acid molecule and in the 2D polymer films organized from such macromolecular chains.