Electronic and Lattice Dynamics in The Photoinduced Ionic-to-Neutral Phase Transition in a One-Dimensional Extended Peierls-Hubbard Model

TL;DR

This study investigates the real-time electronic and lattice dynamics during photoinduced ionic-to-neutral phase transitions in a one-dimensional model, revealing how domain growth, disorder, and solitons influence the transition process.

Contribution

It provides a detailed simulation of charge and lattice dynamics in a one-dimensional model, highlighting the effects of excitation intensity and disorder on phase transition mechanisms.

Findings

Neutral domains grow with increased photoexcitation intensity.

Above threshold, the neutral phase is achieved.

Lattice disorder leads to soliton formation that hinders the transition.

Abstract

Real-time dynamics of charge density and lattice displacements is studied during photoinduced ionic-to-neutral phase transitions by using a one-dimensional extended Peierls-Hubbard model with alternating potentials for the one-dimensional mixed-stack charge-transfer complex, TTF-CA. The time-dependent Schr\"odinger equation and the classical equation of motion are solved for the electronic and lattice parts, respectively. We show how neutral domains grow in the ionic background. As the photoexcitation becomes intense, more neutral domains are created. Above threshold intensity, the neutral phase is finally achieved. After the photoexcitation, ionic domains with wrong polarization also appear. They quickly reduce the averaged staggered lattice displacement, compared with the averaged ionicity. As the degree of initial lattice disorder increases, more solitons appear between these ionic domains with different polarizations, which obstruct the growth of neutral domains and slow down the transition.