Volume 224, 2020

Weight dependence of local exchange–correlation functionals in ensemble density-functional theory: double excitations in two-electron systems

Abstract

Gross–Oliveira–Kohn (GOK) ensemble density-functional theory (GOK-DFT) is a time-independent extension of density-functional theory (DFT) which allows the computation of excited-state energies via the derivatives of the ensemble energy with respect to the ensemble weights. Contrary to the time-dependent version of DFT (TD-DFT), double excitations can be easily computed within GOK-DFT. However, to take full advantage of this formalism, one must have access to a weight-dependent exchange–correlation functional in order to model the infamous ensemble derivative contribution to the excitation energies. In the present article, we discuss the construction of first-rung (i.e., local) weight-dependent exchange–correlation density-functional approximations for two-electron atomic and molecular systems (He and H2) specifically designed for the computation of double excitations within GOK-DFT. In the spirit of optimally-tuned range-separated hybrid functionals, a two-step system-dependent procedure is proposed to obtain accurate energies associated with double excitations.

Graphical abstract: Weight dependence of local exchange–correlation functionals in ensemble density-functional theory: double excitations in two-electron systems

Associated articles

Article information

Article type
Paper
Submitted
13 Maijs 2020
Accepted
15 Jūn. 2020
First published
15 Jūn. 2020

Faraday Discuss., 2020,224, 402-423

Weight dependence of local exchange–correlation functionals in ensemble density-functional theory: double excitations in two-electron systems

C. Marut, B. Senjean, E. Fromager and P. Loos, Faraday Discuss., 2020, 224, 402 DOI: 10.1039/D0FD00059K

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