Electronic theory of surface segregation in the coherent potential approximation: The surface segregation in CoNi, IrPt and RhPt

The surface segregation in CoNi, IrPt and RhPt is calculated within the coherent potential approximation. It is assumed that the metals form substitutional alloys and only diagonal disorder is taken into account. The condition of the local neutrality resulting in the presence of diagonal potentials in the Hamiltonian is also introduced. The alloys are selected in such a way that: (i) the non-diagonal disorder can be neglected with a relatively good approximation, (ii) the d-band filling is not too large to ensure the procedure of determining diagonal potentials from the local neutrality condition to work properly and (iii) the experimental data are available.