Van der Waals forces in the local-orbital Density Functional TheoryM. A. Basanta, Y. J. Dappe, J. Ortega and F. Flores
Departamento de Física Teórica de la Materia Condensada Universidad Autónoma de Madrid - Madrid, E-28049 Spain
received 24 November 2004; accepted in final form 14 March 2005
published online 6 April 2005
Van der Waals forces are analyzed in a Density Functional Theory, using a "local orbital occupancy" formulation and second-order perturbation theory. In this approach, the exchange-correlation energy as well as the van der Waals forces are written as a function of the orbital occupation numbers. We present a detailed discussion of the - case and calculate the Density Functional-van der Waals energy of the system. Our analysis also suggests an alternative approach for including van der Waals forces in the local-orbital DFT formulation, namely, to introduce an effective hopping interaction between the orbitals of both atoms. Our results for the and dimers show the validity and the accuracy of our proposed DFT-van der Waals approach.
71.15.Mb - Density functional theory, local density approximation, gradient and other corrections.
34.20.Gj - Intermolecular and atom-molecule potentials and forces.
71.15.Nc - Total energy and cohesive energy calculations.
© EDP Sciences 2005