ELECTRONIC-PROPERTIES OF BINARY-ALLOYS THROUGH DIRECT CONFIGURATIONAL AVERAGING - COMPARISON WITH CONVENTIONAL METHODS

Effective cluster interactions (ECIs) are calculated from electronic tight-binding Hamiltonians of random binary systems by the recently developed method of direct configurational averaging (DCA). The key issue addressed presently is the correspondence that DCA has to the conventional approach of the coherent potential approximation generalized perturbation method (CPA-GPM) and the recently introduced Connolly-Williams method (CWM). Calculations obtained by DCA of ECIs and energies of ordering and of the disordered state are compared with analogous results of the CPA-GPM and the CWM. Since the definition of the ECIs and the philosophy of approach differ among the three methods, correspondence of the DCA formalism with the other two is also discussed. Convergence of DCA-obtained quantities is examined and general behaviors arising from random averaging are assessed. © 1990 The American Physical Society.