Non-Adiabatic Approximations in Time-Dependent Density Functional Theory: Progress and Prospects

TL;DR

This paper reviews the development and challenges of non-adiabatic exchange-correlation functionals in time-dependent density functional theory, emphasizing the importance of memory effects for accurate electronic spectra and dynamics.

Contribution

It provides a comprehensive overview of progress and future prospects in creating practical non-adiabatic functionals with memory dependence.

Findings

Non-adiabatic functionals improve accuracy in electronic spectra.

Memory-dependent functionals are challenging to develop.

Adiabatic approximations ignore important memory effects.

Abstract

Time-dependent density functional theory continues to draw a large number of users in a wide range of fields exploring myriad applications involving electronic spectra and dynamics. Although in principle exact, the predictivity of the calculations is limited by the available approximations for the exchange-correlation functional. In particular, it is known that the exact exchange-correlation functional has memory-dependence, but in practise adiabatic approximations are used which ignore this. Here we review the development of non-adiabatic functional approximations, their impact on calculations, and challenges in developing practical and accurate memory-dependent functionals for general purposes.