Electron dynamics in extended systems within real-time time-dependent density functional theory

TL;DR

This paper reviews recent developments in real-time time-dependent density functional theory for extended systems, focusing on computational aspects, limitations in electron-electron scattering, and improvements in exchange-correlation descriptions.

Contribution

It provides a comprehensive overview of recent implementations, computational challenges, and methodological improvements in RT-TDDFT for complex extended systems.

Findings

Analysis of computational cost and boundary conditions

Comparison with many-body perturbation theory for scattering

Review of exchange-correlation improvements

Abstract

Due to a beneficial balance of computational cost and accuracy, real-time time-dependent density functional theory has emerged as a promising first-principles framework to describe electron real-time dynamics. Here we discuss recent implementations around this approach, in particular in the context of complex, extended systems. Results include an analysis of the computational cost associated with numerical propagation and when using absorbing boundary conditions. We extensively explore the shortcomings for describing electron-electron scattering in real time and compare to many-body perturbation theory. Modern improvements of the description of exchange and correlation are reviewed. In this work, we specifically focus on the Qb@ll code, which we have mainly used for these types of simulations over the last years, and we conclude by pointing to further progress needed going forward.