A new form for the kinetic energy-density functional for many-electron systems

Abstract

A new simple form for the atomic kinetic energy-density functional (t) is proposed as a sum of the Thomas-Fermi term and a radial correction term, namely, t [p] = (3/10) (3π ²)^2/3p^5/3 - (^1/40)(r.∇ p)/r², where the first term is the Thomas-Fermi term and p(r) is the Hartree-Fock atomic density. The correction term is part of the -(1/4)∇²p term which occurs in the kinetic energy density; it adds mainly terms of O(Z²) and O(Z^5/3) to the Z^7/3 atomic Thomas-Fermi energy. The above form generally displays improved local and global behaviour for atomic kinetic energies. Besides satisfying the virial theorem, it gives rise to chemical binding in molecules.