First-principles calculations for solid solubility limit of impurities in metals: many-body interaction effect

We present the first-principles calculations for the temperature dependence of the solid solubility limit of Rh impurities in Pd, which is segregated at low temperatures and becomes disordered at high temperatures. The impuri ty pair and cluster interaction energies, which are needed to obtain the in ternal energy of the free energy, are calculated by use of the KKR-Green's function method for impurities combined with density functional theory in t he generalized gradient approximation of Perdew and Wang, while the configu rational entropy is treated by the cluster variation method in the tetrahed ron approximation. It is shown that the observed temperature dependence of the solid solubility limit of Rh in Pd can be reproduced almost completely by the present first-principles calculations including the impurity cluster interaction energies up to the tetrahedron. (C) 2001 Elsevier Science BN. All rights reserved.