ABINITIO METHOD FOR BAND-STRUCTURE CALCULATIONS ON STRUCTURALLY DISORDERED MATERIALS - VIBRATIONAL PROPERTIES OF 4D TRANSITION-METALS

An approximate method for electron band-structure calculations on stru cturally disordered materials is presented. Our approach is essentiall y a linear-muffin-tin-orbital calculation in which the structure matri x of a disordered supercell is reduced to the size of one atom per uni t cell through an averaging procedure. Potential fluctuations are incl uded by treating Madelung shifts as perturbations. A lattice of atoms with uncorrelated displacements is studied, and we show how total-ener gy results should be compared with experimental thermodynamic informat ion. In particular, we expect an almost quasiharmonic behavior for cal culated thermodynamic properties. We use our method to calculate Debye temperatures THETA(D) for all 4d transition metals from Zr to Pd in t he bcc, fcc, and hcp structures, and we discuss the physical reasons f or variations in THETA(D). Anharmonic effects are studied by determini ng thermal expansions and bulk moduli as functions of temperature. Bei ng an ab initio calculation, our results are in very good agreement wi th experiment. Electronic energy spectra at finite temperatures are pr esented and we comment on similarities with previous results on liquid transition metals.