INTERSTITIAL ORBITALS FOR SIMPLE METALS - 2D SYSTEMS

The relevance of the interstitial model for the metallic bond has been studied on 2D simple metal. lattices: the lithium square lattice and the magnesium triangular one. As on 1D systems the valence electron de nsity is essentially interstitial on both systems. However, the magnet ic treatment of the inverse lattice problem-up to now always associate d with the interstitial description of simple metals-was proven false on the magnesium lattice which remains highly delocalized, The reasons of the different behavior of the Li and Mg systems have been investig ated, as well as the conductivity problem associated with a magnetic d escription of the inverse lattice. A phase transition, semiconductor v ersus insulator, has been exhibited on the Mg lattice. The insulator p hase (long distances) corresponding to an atom-centered solution, the semiconductor phase (short distances) corresponding to an interstitial solution.