Single excitation energies obtained from the ensemble “HOMO–LUMO gap”: Exact results and approximations

T Gould, Z Hashimi, L Kronik… - The journal of physical …, 2022 - ACS Publications
In calculations based on density functional theory, the “HOMO–LUMO gap”(difference
between the highest occupied and lowest unoccupied molecular orbital energies) is often …

Exact excited-state functionals of the asymmetric Hubbard dimer

S Giarrusso, PF Loos - The Journal of Physical Chemistry Letters, 2023 - ACS Publications
The exact functionals associated with the (singlet) ground state and the two singlet excited
states of the asymmetric Hubbard dimer at half-filling are calculated using both Levy's …

Asymptotic Behavior of the Exchange‐Correlation Energy Density and the Kohn‐Sham Potential in Density Functional Theory: Exact Results and Strategy for …

E Kraisler - Israel Journal of Chemistry, 2020 - Wiley Online Library
Density functional theory (DFT) is nowadays the leading theoretical framework for quantum
description of materials from first principles. Being an exact theory on one hand and …

Ensemble density functional theory: Insight from the fluctuation-dissipation theorem

T Gould, G Stefanucci, S Pittalis - Physical Review Letters, 2020 - APS
Density functional theory can be generalized to mixtures of ground and excited states, for the
purpose of determining energies of excitations using low-cost density functional …

Hartree and exchange in ensemble density functional theory: Avoiding the nonuniqueness disaster

T Gould, S Pittalis - Physical review letters, 2017 - APS
Ensemble density functional theory is a promising method for the efficient and accurate
calculation of excitations of quantum systems, at least if useful functionals can be developed …

How interatomic steps in the exact Kohn–Sham potential relate to derivative discontinuities of the energy

MJP Hodgson, E Kraisler, A Schild… - The journal of physical …, 2017 - ACS Publications
Accurate density functional calculations hinge on reliable approximations to the unknown
exchange-correlation (xc) potential. The most popular approximations usually lack features …

Exact conditions for ensemble density functional theory

TR Scott, J Kozlowski, S Crisostomo, A Pribram-Jones… - Physical Review B, 2024 - APS
Ensemble density functional theory (EDFT) is a promising alternative to time-dependent
density functional theory for computing electronic excitation energies. Using coordinate …

Individual correlations in ensemble density functional theory: State-and density-driven decompositions without additional Kohn-Sham systems

E Fromager - Physical Review Letters, 2020 - APS
Gould and Pittalis [Phys. Rev. Lett. 123, 016401 (2019) PRLTAO 0031-9007
10.1103/PhysRevLett. 123.016401 recently revealed a density-driven (DD) correlation …

Direct extraction of excitation energies from ensemble density-functional theory

Z Yang, A Pribram-Jones, K Burke, CA Ullrich - Physical Review Letters, 2017 - APS
A very specific ensemble of ground and excited states is shown to yield an exact formula for
any excitation energy as a simple correction to the energy difference between orbitals of the …

Density-driven correlations in many-electron ensembles: Theory and application for excited states

T Gould, S Pittalis - Physical Review Letters, 2019 - APS
Density functional theory can be extended to excited states by means of a unified variational
approach for passive state ensembles. This extension overcomes the restriction of the …