M S Laad and L Craco 2005 J. Phys.: Condens. Matter 17 4765 doi:10.1088/0953-8984/17/30/004
M S Laad1 and L Craco2
Show affiliationsWe 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 self-consistently embedded cluster. This cluster problem is then solved using the equations of motion technique. The CPA is recovered for cluster size Nc = 1. Various new features, compared to those observed in CPA, and related to repeated scattering on pairs of sites, reflecting the effect of short-range order are clearly visible in the density of states. It is explicitly shown that the cluster-CPA method always yields a positive-definite density of states. 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.
71.23.An Theories and models; localized states
71.30.+h Metal-insulator transitions and other electronic transitions
Issue 30 (3 August 2005)
Received 5 May 2005, in final form 22 June 2005
Published 15 July 2005
M S Laad and L Craco 2005 J. Phys.: Condens. Matter 17 4765
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