Nonadiabatic Time-Dependent Spin-Density Functional Theory for strongly correlated systems

TL;DR

This paper introduces a nonadiabatic time-dependent spin-density functional theory (TDSDFT) that effectively models strongly correlated electron systems, capturing excited states and ultrafast responses more accurately than previous adiabatic methods.

Contribution

It develops a nonadiabatic exchange-correlation kernel based on the Hubbard model, enabling better simulation of strongly correlated systems in and out of equilibrium.

Findings

Reproduces key spectral features of Hubbard models

Outperforms adiabatic approaches in strongly correlated regimes

Reduces computational requirements for nanostructure simulations

Abstract

We propose a nonadiabatic time-dependent spin-density functional theory (TDSDFT) approach for studying the single-electron excited states and the ultrafast response of systems with strong electron correlations. The correlations are described by the correlation part of the nonadiabatic exchange-correlation (XC) kernel, which is constructed by using some exact results for the Hubbard model of strongly correlated electrons. We demonstrate that the corresponding nonadiabatic XC kernel reproduces main features of the spectrum of the Hubbard dimer and infinite-dimensional Hubbard model, some of which are impossible to obtain within the adiabatic approach. The theory may be applied for DFT study of strongly correlated electron systems in- and out-of-equilibrium, including the important case of nanostructures, for which it leads to a dramatic reduction of necessary computational power.