Realizations of the noninteracting kinetic energy functional enhancement factor through local-scaling transformations:: Atoms

Within the framework of the local-scaling version of density functional theory, we deal with the problem of constructing approximate forms for the noninteracting kinetic energy functional T-s[rho]. For this purpose, we resort to density-dependent orbitals generated by means-of local-scaling transformations. We examine the use of different types of initial orbital sets for the generation of the density-dependent orbitals and, in particular, analyze the realization of the enhancement factor in terms of locally scaled plane waves, orthogonal polynomials (Laguerre), and generalized Slater-type orbitals. Application to the Na and Al atoms shows the feasibility of representing the enhancement factor in closed form, in particular when generalized Slater-type orbitals are used. (C) 2003 Wiley Periodicals, Inc.