REAL-SPACE TIGHT-BINDING APPROACH TO STABILITY AND ORDER IN SUBSTITUTIONAL MULTICOMPONENT ALLOYS

A real-space approach based on the tight-binding approximation for stu dying electronic structure properties and stability and order in subst itutional multicomponent alloys is presented. First. for a chemically random alloy based on a periodic lattice, we show that the coherent po tential approximation equations can be solved self-consistently in rea l space with the same accuracy currently achieved in reciprocal space. The resulting one-electron Green function is given by a continued fra ction expansion, and this analytic form can be conveniently used to de termine alloy properties, and in particular the energetics. Second, co mbined with an orbital-peeling technique, this method allows in a very efficient way the calculation of the effective cluster interactions w hich enter the expression of the configurational part of the total ene rgy for describing order-disorder phenomena in alloys. Finally, we pre sent some applications and briefly discuss the possible extensions of this approach.