Degeneracy and size consistency in electronic density functional theory

Abstract

The electronic structure calculations based upon energy density functionals are highly successful and widely used both in solid state physics and quantum chemistry. Moreover, the Hohenberg-Kohn theorems and the Kohn-Sham method provide them with a firm basis. However, several basic issues are not solved, and hamper the progress to achieve high accuracy. In this paper we focus on the conceptual problem of size consistency, basing our analysis on the non-intensive character of the (spin) electronic density in the presence of degeneracy. We also briefly discuss some of the issues concerning fractional electron numbers from the same point of view, analyzing the behavior of the exact functionals for the He and the Hooke's atom series when the number of electrons fluctuates between one and two.

submitted to Journal of Physics: Conference Series

References in corpus (4)

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• Restoring size consistency of approximate functionals constructed from the adiabatic connection
• Assessment of interaction-strength interpolation formulas for gold and silver clusters
• On derivatives of the energy with respect to total electron number and orbital occupation numbers. A critique of Janak's theorem
• Local and global interpolations along the adiabatic connection of DFT: A study at different correlation regimes
• Density functional theory for fractional charge: Locality, size consistency, and exchange-correlation