Cluster coherent potential approximation for electronic structure of disordered alloys

Abstract

We extend the single-site coherent potential approximation (CPA) to include the effects of non-local disorder correlations (alloy short-range order) on the electronic structure of random alloy systems. This is achieved by mapping the original Anderson disorder problem to that of a selfconsistently embedded cluster. This cluster problem is then solved using the equations of motion technique. The CPA is recovered for cluster size $N_c=1$, and the disorder averaged density-of-states (DOS) is always positive definite. Various new features, compared to those observed in CPA, and related to repeated scattering on pairs of sites, reflecting the effect of SRO are clearly visible in the DOS. It is explicitly shown that the cluster-CPA method always yields positive-definite DOS. Anderson localization effects have been investigated within this approach. In general, we find that Anderson localization sets in before band splitting occurs, and that increasing partial order drives a continuous transition from an Anderson insulator to an incoherent metal.

arXiv comment7 pages, 6 figures. submitted to PRB

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• Possible Metal/Insulator Transition at B=0 in Two Dimensions
• Typical medium theory of Anderson localization: A local order parameter approach to strong disorder effects
• Systematic and Causal Corrections to the Coherent Potential Approximation
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Cited by in corpus (3)

• Coherent potential approximation for spatially correlated disorder
• Real-space cluster dynamical mean-field approach to the Falicov-Kimball model: An alloy-analogy approach
• Effective bands and band-like electron transport in amorphous solids