LATTICE-DYNAMICS, THERMAL-EXPANSION, AND 3RD-ORDER ELASTIC-CONSTANTS OF SEMINOBLE METALS

General expressions to calculate the first, second-, and third-order coupling parameters considering a general interatomic model that includes both two- and three-body uncoupled forces are given. These formulae are applied to deduce the analytic expressions of the pressure, the second-(SOEC), and third-order (TOEC) elastic constants and the dynamical matrix and its strain derivative for the case of metals with face-centred cubic (f.c.c.) structure and considering two-body interactions up to third neighbours and common nearest-neighbour three-body force ones. A scheme of parametrization is proposed and the four independent parameters of the model are estimated. Within this framework the lattice contribution to the dispersion curves, the TOEC's, and the Gruneisen function for Ni, Pd, and Pt are calculated and compared with the values obtained from experimental data. Also the microscopic information the model gives, particularly the importance of three-body forces and the fulfilment of the Gruneisen rule is analyzed.