Physical signatures of discontinuities of the time-dependent exchange-correlation potential

TL;DR

This paper investigates the physical effects of discontinuities in the time-dependent exchange-correlation potential within TDDFT, demonstrating their impact on electron dynamics during ionization and dissociation processes.

Contribution

It shows that the self-interaction corrected adiabatic local-density approximation captures these discontinuities and highlights their significance in real-time quantum simulations.

Findings

Discontinuities affect electron population during dissociation.

Self-interaction correction captures potential steps.

Discontinuities influence ionization and charge transfer.

Abstract

The exact exchange-correlation (XC) potential in time-dependent density-functional theory (TDDFT) is known to develop steps and discontinuities upon change of the particle number in spatially confined regions or isolated subsystems. We demonstrate that the self-interaction corrected adiabatic local-density approximation for the XC potential has this property, using the example of electron loss of a model quantum well system. We then study the influence of the XC potential discontinuity in a real-time simulation of a dissociation process of an asymmetric double quantum well system, and show that it dramatically affects the population of the resulting isolated single quantum wells. This indicates the importance of a proper account of the discontinuities in TDDFT descriptions of ionization, dissociation or charge transfer processes.