Europhys. Lett.
Volume 70, Number 3, May 2005
Page(s) 355 - 361
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 06 April 2005
Europhys. Lett., 70 (3), pp. 355-361 (2005)
DOI: 10.1209/epl/i2004-10495-7

Van der Waals forces in the local-orbital Density Functional Theory

M. 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 $\chem{He}$-$\chem{He}$ 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 $\chem{He}$ and $\chem{Ne}$ 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