Interatomic Potentials in Simple Metals

Abstract

Abstract In this chapter, quantum-based interatomic potentials for simple metals are derived starting from the corresponding cohesive-energy functional established in Chapter 2 via density functional theory and pseudopotential perturbation theory. This functional is expressed in reciprocal space for a general nonlocal pseudopotential and then transformed to the desired real-space representation in terms of a volume term and a volume-dependent pair potential. To allow full evaluation of the pseudopotential and the pair potential from first principles, a self-consistent electron screening calculation is also made. Accurate pair potentials so calculated have been obtained for a number of simple metals, including Na, Mg and Al prototypes, using two different optimized forms of nonlocal pseudopotential: the basic Austin, Heine and Sham form employed in generalized pseudopotential theory, and the norm conserving model potential form of Dagens, Rasolt and Taylor. Efficient practical methods to deal with the long-range Friedel oscillations in the pair potential arising from the self-consistent screening are also discussed.