Fast transport and relaxation of vibrational energy in polymer chains

TL;DR

This paper analyzes vibrational energy transport in polymer chains, revealing ballistic, diffusive, and directed diffusive regimes, with a continuous crossover between diffusive regimes and a discontinuous transition from ballistic to diffusive transport, supported by an exact solution.

Contribution

It provides an exact analytical solution for vibrational energy transport in oligomeric chains, characterizing different transport regimes and their transitions, aligning with recent experimental observations.

Findings

Identifies three transport regimes: ballistic, diffusive, and directed diffusive.

Derives an exact solution for excitation density in space-time.

Shows continuous crossover between diffusive regimes and discontinuous transition from ballistic to diffusive transport.

Abstract

We investigate ballistic vibrational energy transport through optical phonon band in oligomeric chains in the presence of decoherence. An exact solution is obtained for the excitation density in the space-time representation in the continuous limit and this solution is used to characterize the energy transport time and intensity. Three transport mechanisms are identified such as ballistic, diffusive and directed diffusive regimes, occurring at different distances and time ranges. The crossover between the two diffusive regimes is continuous, while the switch between the ballistic and diffusive mechanisms occurs in discontinuous manner in accord with the recent experimental data on energy transport in perfluoroalkanes.