Photogeneration Dynamics of a Soliton Pair in Polyacetylene

TL;DR

This study numerically investigates how a photogenerated electron-hole pair in polyacetylene evolves into a soliton pair, revealing various dynamic behaviors influenced by disorder and lattice interactions.

Contribution

It introduces a numerical simulation of soliton pair formation from photoexcited states in polyacetylene using the SSH Hamiltonian with disorder effects.

Findings

Soliton pairs form after initial lattice oscillations.

Disorder influences soliton separation and dynamics.

Different behaviors include solitons running apart or forming bound states.

Abstract

Dynamical process of the formation of a soliton pair from a photogenerated electron-hole pair in polyacetylene is studied numerically by adopting the SSH Hamiltonian. A weak local disorder is introduced in order to trigger the formation. Starting from an initial configuration with an electron at the bottom of the conduction band and a hole at the top of the valence band, separated by the Peierls gap, the time dependent Schr${\rm \ddot{o}}$ndinger equation for the electron wave functions and the equation of motion for the lattice displacements are solved numerically. After several uniform oscillations of the lattice system at the early stage, a large distortion corresponding to a pair of a soliton and an anti-soliton develops from a point which is determined by the location and type of the disorder. In some cases, two solitons run in opposite directions, leaving breather like oscillations behind, and in other cases they form a bound state emitting acoustic lattice vibrational modes.