Koopmans’ condition in self-interaction-corrected density-functional theory

Abstract

We investigate from a practitioner's point of view the computation of the ionization potential (IP) within density functional theory (DFT). DFT with (semi-)local energy-density functionals is plagued by a self-interaction error which hampers the computation of IP from the single-particle energy of the highest occupied molecular orbital (HOMO). The problem may be cured by a self interaction correction (SIC) for which there exist various approximate treatments. We compare the performance of the SIC proposed by Perdew and Zunger with the very simple average-density SIC (ADSIC) for a large variety of atoms and molecules up to larger systems as carbon rings and chains. Both approaches to SIC provide a large improvement to the quality of the IP if calculated from the HOMO level. The surprising result is that the simple ADSIC performs even better than the original Perdew-Zunger SIC (PZSIC) in the majority of the studied cases.

Forward-backward asymmetry of photoemission inC60excited by few-cycle laser pulses

“…As a full SIC treatment is computationally cumbersome [38], we use it in a simplified, but reliable and efficient version as an average density SIC (ADSIC) [39]. The ADSIC suffices to put the single-particle energies into right relation to continuum threshold such that the ionization potential (IP) is correctly reproduced in a great variety of systems [40] from simple atoms to large organic molecules. In this context, a correct description of IP is crucial for photoemission excited by external fields, in particular by strong fields as it is assumed to be dominated by electrons in the highest occupied molecular orbitals (HOMO) [41].…”

On the dynamics of photo-electrons in C60

“…In practice, we use an average-density self-interaction correction [45]. This formalism is simple and yet reliable for a broad variety of molecules including covalently bound systems [46]. To analyze observables from electronic emission, we apply absorbing boundary conditions following [40,47].…”

Multiplasmon excitations in electron spectra of small systems irradiated by swift charged projectiles

“…This is because we refitted the parameters of the Goedecker-like pseudopotential to allow us to use a mesh size of 0.7 a 0 . If we use the original value of the Goedecker pseudopotential [23], we obtain an IP of 11.3 eV [49], much closer to the experimental value. However, that would mean a mesh size twice smaller (0.36 a 0 ), that is huge numerical boxes which represent a great hindrance for the dynamical calculations we present here.…”