Augmented Space Formalism For Diagonal And Off-Diagonal Disordered Alloys

A general treatment for electronic states of disordered alloys, including composition-dependent off-diagonal Hamiltonian matrix elements is presented. The recursion method within the augmented space of a disordered lattice is exploited. The main novelty is the simple description of the states of this space by a binary logic to allow a manageable use of recurrence relations. Several examples of one-dimensional disordered alloys are considered, and comparison is performed between the electronic structure obtained with our procedure and numerical simulation of small clusters.