Comparison of the electronic states of alloys from the coherent potential approximation and an order-N calculation

For historical reasons, the coherent potential approximation was originally proposed for isomorphous models of alloys in which all the atoms of a give n species are assumed to have the same charge distribution. Order-N methods for density-functional theory local-density approximation calculations of the electronic structure for clusters of hundreds or thousands of atoms dem onstrate that a polymorphous model, in which each atom is different, is mor e realistic. The predictive ability of isomorphous coherent potential appro ximations is studied by comparison with order-N calculations.