A density-functional study of van der Waals forces: He interaction with a semiconductor surface.

In this paper we present a Density Functional study of the interaction of a Helium atom with the (110) surface of InSb. On the basis of calculations within the Local Density Approximation (LDA) and the Generalized Gradient Approximation (GGA) we conclude that the latter is inadequate to describe the mecllanism of the interaction as already observed for the potential energy curves of rare-gas diatomic systems. Moreover we discuss the full He-surface potential within LDA, find the preferential site for trapping of the atom on the surface and comment. on the validity of the Esbjerg and Norskov approximation for the repulsive term in the Helium scattering potential.