Variational test on the relationship between gradient expansion terms in the kinetic energy density functional

Abstract

Brief Reports are short papers which report on completed research which, while meeting the usual Physicai Review standards of scientific quality, does not warrant a regular article (A. ddenda to papers previously published in the Physical Review by the same authors are included in Brief Reports )A . Brief Report may be no longer than 3~~printed pages and must be accompanied by an abstract T. he same publication schedule as for regular articles is followed, and page proofs are sent to authors. By using an approximate analytical trial density and the consideration of an energy density functional which includes a modified gradient correction, the relationship between the zeroth-order and the first gradient correction is tested and the results compared with those obtained through the use of Hartree-Fock-Roothaan-Clementi densities.