The Journal of Physical chemistry A [LCQS]

Abstract:

A Kohn–Sham (KS) density-functional energy expression is derived for any (ground or excited) state within a given many-electron ensemble along with the stationarity condition it fulfills with respect to the ensemble density, thus giving access to both physical energy levels and individual-state densities, in principle exactly. We also provide working equations for the evaluation of the latter from the true static ensemble density–density linear response function. Unlike in Gould’s recent ensemble potential functional approach to excited states [arXiv:2404.12593], we use the ensemble density as sole basic variable. While a state-specific KS potential naturally emerges from the present formalism, at the exact ensemble Hartree-exchange-only (Hx) level of approximation, the standard implementation of orbital-optimized density functional theory for excited states is recovered when recycling the regular ground-state Hx-correlation functional in this context.

 

Reference:

Ensemble Density Functional Theory of Ground and Excited Energy Levels

Emmanuel Fromager

The Journal of Physical chemistry A, First published: 20 january 2025 – DOI: https://doi.org/10.1021/acs.jpca.4c06744

Contact :

Emmanuel Fromager (équipe LCQS, Chimie Quantique de Strasbourg), Institut de Chimie de Strasbourg, UMR 7177.