Generalized coherent-potential method for disordered systems. II. Numerical results

An elaboration and numerical study is presented for a coherent-potential- alloy (CPA) theory which gives the next step beyond the single-site CPA by including nearest-neighbor correlations. The theory includes all aspects of disorder including short-range order. Although the theory does not strictly have the Herglotz property, it gives physically reasonable results. Numerical results are presented for the electron density of states of binary alloys which show the effects of diagonal and off-diagonal disorder, nearest-neighbor correlations, shielding of the potential, and short-range order. Short-range order is shown to have the largest effect on the shape of the density of states.