CATION POLARIZATION AND THE CRYSTAL-STRUCTURE OF SNO

Tin(II) oxide has an unusual crystal structure (litharge) which exhibi ts numerous 'non-ionic' features, such as nearest neighbour ions of li ke charge and a large lattice energy compared with other oxides of sim ilar cation radius. It is shown that a generic ionic interaction model for oxides, with an ab initio based representation of such many-body effects as ionic polarization and the compression of the oxide ion by its environment, predicts litharge as the lowest energy structure. Cat ion polarization is found to play the dominant role.