Reply to Comment by Holas and March

Abstract

The accompanying Comment by A. Holas and N. H. March [Phys. Rev. A {\bf 66}, 066501 (2002)] is concerned with the issue of whether or not kinetic energy can be represented by an effective local potential, as required for an exact Thomas-Fermi theory equivalent to Kohn-Sham density-functional theory. They dispute [R.K. Nesbet, Phys. Rev. A {\bf 65}, 010502(R) (2001)], which concludes that for more than two electrons the use by Kohn and Sham of the Schrödinger kinetic energy operator is variationally correct, while the equivalent local potential required for a valid Thomas-Fermi theory, a Fréchet functional derivative of the Kohn-Sham ground-state kinetic energy functional, does not exist. The argument of Holas and March is clearly invalid for the simple example of the lowest triplet state of a two-electron atom with noninteracting electrons. Why this fails, as do earlier arguments in the literature, has been explained in recent publications, summarized here.