From Kohn-Sham to Many-Electron Energies via Step Structures in the Exchange-Correlation Potential.

ABSTRACT: Accurately describing excited states within Kohn-Sham (KS) density functional theory (DFT), particularly those which induce ionization and charge transfer, remains a great challenge. Common exchange-correlation (xc) approximations are unreliable for excited states owing, in part, to the absence of a derivative discontinuity in the xc energy (Δ), which relates a many-electron energy difference to the corresponding KS energy difference. We demonstrate, analytically and numerically, how the relationship between KS and many-electron energies leads to the step structures observed in the exact xc potential in four scenarios: electron addition, molecular dissociation, excitation of a finite system, and charge transfer. We further show that steps in the potential can be obtained also with common x

SUBMITTER: Kraisler E 

PROVIDER: S-EPMC8363072 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature