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- Ruban, Andrei V., et al.
(författare)
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Theoretical investigation of bulk ordering and surface segregation in Ag-Pd and other isoelectornic alloys
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75, s. 054113-1-05411316
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Tidskriftsartikel (refereegranskat)abstract
- Bulk ordering in Ag-Pd and other isoelectronic alloys is investigated theoretically by a number of first-principles techniques. The electronic structure and total energy have been calculated by the Green's function Korringa-Kohn-Rostocker and full-potential plane wave methods. The effective cluster interactions of the Ising-type Hamiltonian have been obtained by the screened generalized perturbation method. They reveal a complex concentration-dependent ordering behavior in these alloys due to band filling and Fermi surface effects. In particular we show that long-period superstructures are gradually stabilized by a great number of relatively weak long-range effective pair- and three-site interactions, which can be seen as collective effect. A similar complex concentration dependence is also found for surfaces of Ag-Pd alloys. The surface composition of the (111) and (100) surface of Ag75Pd25, Ag50Pd50, and Ag33Pd67 alloys have been then investigated by the surface Green's function technique and the screened generalized perturbation method for the effective interactions of the Ising-type Hamiltonian and the grand canonical Monte Carlo method for statistical thermodynamic simulations at finite temperatures. We compare our results with experimental data and other theoretical calculations.
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