On the degeneracy of atomic states within exact-exchange (spin-) density functional theory

Abstract

The problem of degenerate ground states of open-shell atoms is investigated in spin-restricted and unrestricted density functional theory using the exact exchange energy functional. For the spin-unrestricted case, spurious energy splittings of the order of 2 to 3 kcal/mol are found for atoms of the second and third period which is larger than the splittings obtained from recently proposed approximate exchange functionals depending explicitly on the current density. In remarkable contrast, for spin-restricted calculations the degeneracy of different atomic ground states is recovered to within less than 0.6 kcal/mol.

arXiv comment5 pages

References in corpus (3)

• Simple iterative construction of the optimized effective potential for orbital functionals, including exact exchange
• Optimized Effective Potential made simple: Orbital functionals, orbital shifts, and the exact Kohn-Sham exchange potential
• Degeneracy in Density Functional Theory: Topology in v- and n-Space

Cited by in corpus (4)

• 'Hartree-exchange' in ensemble density functional theory: Avoiding the non-uniqueness disaster
• Fully numerical calculations on atoms with fractional occupations. Range-separated exchange functionals
• Charge transfer excitations from exact and approximate ensemble Kohn-Sham theory
• Optimized Effective Potential Method in Current-Spin Density Functional Theory