AUGMENTED SPACE FORMALISM FOR DIAGONAL AND OFF-DIAGONAL DISORDERED ALLOYS

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