How to tell an atom from an electron gas: a semi-local index of density inhomogeneity
2003 (English)In: Acta physica et chimica debrecina, Vol. 36, no 25Article in journal (Refereed) Published
From a global perspective, the density of an atom is strongly inhomogeneous and not at all like the density of a uniform or nearly-uniform electron gas. But, from the semi-local or myopic perspective of standard density functional approximations to the exchange-correlation energy, it is not so easy to tell an atom from an electron gas. We address the following problem: Given the ground-state electron density n and orbital kinetic energy density in the neighborhood of a point r, can we construct an inhomogeneity index which approaches zero for weakly-inhomogeneous densities and unity for strongly-inhomogeneous ones? The solution requires not only the usual local ingredients of a meta-generalized gradient approximation, but also r and r2. The inhomogeneity index is displayed for atoms, and for model densities of metal surfaces and bulk metals. Scaling behavior and a possible application to functional interpolation are discussed.
Place, publisher, year, edition, pages
2003. Vol. 36, no 25
IdentifiersURN: urn:nbn:se:kth:diva-6785OAI: oai:DiVA.org:kth-6785DiVA: diva2:11594
QC 201008302005-09-232005-09-232010-08-31Bibliographically approved