Explicit particle-number dependence in density functional theory

Abstract

With rare exceptions, explicit particle number dependence (Ne-dependence) in approximate density functionals is viewed as a serious deficiency because of apparent size-consistency issues. In contrast, there are multiple manifestations of explicit Ne-dependence in density functional bounds (including the Gázquez-Robles kinetic energy bound), constraints, and approximations. We argue that these constitute inescapable motivation for exploring Ne-dependent approximate functionals. Doing so would be consistent with a mostly-ignored result of Lieb about properties of the universal functional. © 2013, Sociedad Química de México.