Calculation of equilibrium geometries and ionization energies of sodium clusters up to Na8

Abstract
Using a combination of two methods, a pseudopotential scheme and a density-functional approximation for the correlation energy, equilibrium geometries of clusters Nan up to n=8 have been studied. The structures of small sodium clusters do not show any resemblance to the metallic lattice. Experimental ionization energies can be reproduced with a maximum error of 3%; the alternancy in their dependence on n is described appropriately and is explained by means of structures composed of Na2 units.