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Analytical Expressions for XC Self‐Energies and Quasiparticle Shifts in Free‐Electron‐Like Materials
Author(s) -
Bechstedt F.
Publication year - 1993
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221780212
Subject(s) - quasiparticle , gw approximation , physics , free electron model , electron , condensed matter physics , local density approximation , band gap , dielectric , self energy , electron density , semiconductor , fermi gas , lattice (music) , electronic band structure , atomic physics , dielectric function , wave function , quantum mechanics , electronic structure , superconductivity , acoustics
Abstract The quasiparticle corrections to the energy bands for free‐electron‐like materials that result within the density‐functional local‐density approximation are discussed. Starting point is the exchange‐correlation self‐energy in GW approximation. The energy band structure is replaced by the empty‐lattice one but including an energy gap and free‐electron wave functions are applied. The screening in the system is described by generalizations of the electron‐gas dielectric function which account for energy gaps in the case of semiconductors and insulators and change over into the Lindhard function (or an approximate one) for completely free particles. Analytical expressions depending on electron density and dielectric constant of the material are obtained for XC self‐energies and quasiparticle shifts. The computed numbers are compared with results of more sophisticated GW calculations. An energy‐dependent extra potential is suggested that can lift the failure of the common local‐density approximation.