The electronic density of states of disordered compounds

Abstract

The electronic properties of liquid alkali metal (Li, Na, K, Rb, Cs)-group IV (Si, Ge, Sn, Pb) alloys have been discussed by the authors using a tight-binding model. Only anion orbitals (=group IV) are taken into account. Disorder is described by a pseudo-lattice, which takes into account local coordination in one of the sublattices (cation or anion) only. It is shown that this approximation is consistent with the usual valence rules used by structural chemists for crystalline structures. The solutions for the density of states of the tight-binding Hamiltonian are studied for a number of pseudo-lattices. The approach outlined is capable of describing the electronic density of states due to various degrees of local order in a sublattice. Some of the peculiarities occurring in the solution of the density of states of certain pseudo-lattices, such as poles outside the band, are discussed.