First-principles calculations for point-defect energies in metals and phase diagrams of binary alloys

We discuss the present status of the first-principles electronic-structure calculations for defect energies in metals. The calculations apply density functional theory in the generalized-gradient approximation of Perdew and W ang, together with a full-potential version of Korringa-Kohn-Rostoker Green 's function method, developed by the Julich group. It is shown that: (1) th e present calculations reproduce very well the experimental results for vac ancy formation energies in metals, as well as the bulk properties such as e quilibrium lattice parameters and bulk moduli of metals; and (2) the type o f the phase diagram of a binary A-B alloy can be characterized by the inter action energies between a pair of impurity B (A) atoms in the host metal A (B). The observed temperature dependence of the solid solubility limit of R h in Pd is also reproduced very well by the free-energy calculations based on the cluster variation method with the pair- (up to the eighth neighbor) and many-body (up to a tetrahedron of first-nearest neighbors) interaction energies, all of which are determined by the present first-principles calcu lations. (C) 2001 Elsevier Science B.V. All rights reserved.