Continuous corrections to the molecular Kohn-Sham gap and virtual orbitals
| dc.creator | Mera, Hector | |
| dc.date | 2008-06-25 | |
| dc.date.accessioned | 2026-07-07T09:46:37Z | |
| dc.date.available | 2026-07-07T09:46:37Z | |
| dc.description | We use projector operators to correct the Kohn-Sham Hamiltonian of density functional theory (KS-DFT) so that the resulting mean-field scheme yields, in finite systems, virtual orbitals and energy gaps in better agreement with those predicted by quasiparticle theory. The proposed correction term is a scissors-like operator of the form $(\hat{I}-\hatρ)δ\hat{H}(\hat{I}-\hatρ)$, where $\hat{I}$ is the identity operator, $\hatρ$ the density matrix of the N-particle system and $δ\hat{H}$ is either the difference between the N+1- and N-particle Kohn-Sham Hamiltonians or a non-self-consistent approximation to it. Such a term replaces the Kohn-Sham virtual orbitals of the $N$-particle system by the HOMO and virtual orbitals of the system with $N+1$ particles in an attempt to mimic a true quasiparticle spectrum. Using a local density approximation (LDA) we compute the gaps of a variety of small molecules finding good agreement with experiment and computationally more demanding methods. For these systems we examine the physical origin of this gap correction and show that so-called band gap discontinuity, $Δ_{xc}$, contains electrostatic contributions that do not originate from the discontinuity in the exchange-correlation potential. The similarity between the corrected and Hartree-Fock virtual orbitals is illustrated and the extent to which the bare LDA virtual orbitals are improved is considered. The lack of band-gap discontinuity and the presence of self-interaction errors in the proposed correction are also discussed. | |
| dc.description | 5 pages, 2 tables, 1 figure. Submitted to Phys. Rev. B | |
| dc.identifier | https://arxiv.org/abs/0806.4060 | |
| dc.identifier | http://arxiv.org/abs/0806.4060 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/163592 | |
| dc.subject | Other Condensed Matter | |
| dc.title | Continuous corrections to the molecular Kohn-Sham gap and virtual orbitals | |
| dc.type | text |