Propagation of Initially Excited States in Time-Dependent Density Functional Theory

TL;DR

This paper investigates how the initial excited state influences the accuracy of time-dependent density functional theory calculations, highlighting the importance of initial-state dependence and the errors caused by common adiabatic approximations.

Contribution

It demonstrates the significance of initial-state dependence in the exact functional and analyzes errors introduced by adiabatic approximations in excited-state propagation.

Findings

Initial-state dependence is crucial for accurate TDDFT calculations.

Adiabatic approximations neglect initial-state dependence, leading to errors.

Model calculations reveal the impact of initial-state effects on excited-state dynamics.

Abstract

Many recent applications of time-dependent density functional theory begin in an initially excited state, and propagate it using an adiabatic approximation for the exchange-correlation potential. This however inserts the excited-state density into a ground-state approximation. By studying a series of model calculations, we highlight the relevance of initial-state dependence of the exact functional when starting in an excited state, and explore the errors inherent in the adiabatic approximation that neglect this dependence.