Electronic structure and charge-transfer-induced cluster formation in alkali-group-IV alloys

In this paper the authors apply model tight-binding calculations to the electronic structure of systems in which there are essentially two covalent interactions: the intracluster interaction U and the intercluster interaction V. The atomic structure is simulated by a modified Bethe lattice which incorporates closed loops as a possibility. The ratio alpha =V/U is an important parameter to be varied. At a distinct value, alpha crit, a metal-non-metal transition takes place. The results are applied to the electronic structure and chemical stability of anion cluster in liquid and solid alkali-group-IV alloys. The physical parameters which govern the process of clustering are discussed.