Gradient expansions in density functional calculations of intermolecular potentials

Abstract

Methods for calculations of intermolecular potentials following the local density approximation (LDA) have earlier been considered, especially for inert gas atom - inert gas atom interactions using the so-called electron gas density functional (EGDF) model. In this Letter some density gradient corrections are discussed and new results are presented. The general conclusion based on the results in the present report seems to be that the EGDF method gives surprisingly good numerical results in the LDA limit for calculations of intermolecular potentials. Corrections due to density gradients contribute only small changes in the sum of the density functional terms considered for the total energy in the EGDF method, but they contribute important corrections to the kinetic energy and to the exchange energy separately. © 2003 Elsevier Science B.V. All rights reserved.