Implication of nonintegral occupation number and Fermi-Dirac statistics in the local-spin-density approximation applied to finite systems

Journal Article · Wed Feb 01 04:00:00 EST 1989 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.39.952· OSTI ID:6532703

Dhar, S

In electronic-structure calculations for finite systems using the local-spin-density (LSD) approximation, it is assumed that the eigenvalues of the Kohn-Sham equation should obey Fermi-Dirac (FD) statistics. In order to comply with this assumption for some of the transition-metal atoms, a nonintegral occupation number is used which also minimizes the total energy. It is shown here that for finite systems it is not necessary that the eigenvalues of the Kohn-Sham equation obey FD statistics. It is also shown that the Kohn-Sham exchange potential used in all LSD models is correct only for integer occupation number. With a noninteger occupation number the LSD exchange potential will be smaller than that given by the Kohn-Sham potential. Ab initio self-consistent spin-polarized calculations have been performed numerically for the total energy of an iron atom. It is found that the ground state belongs to the 3d/sup 6/4s/sup 2/ configuration. The ionization potentials of all the Fe/sup n//sup +/ ions are reported and are in agreement with experiment.

• Research Organization: Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803
• OSTI ID: 6532703
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 39:3; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ATOMS
CONFIGURATION
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
FERMI STATISTICS
GROUND STATES
IONIZATION POTENTIAL
IRON
METALS
OCCUPATION NUMBER
TRANSITION ELEMENTS