Ab initio study of the phonon spectrum, entropy and lattice heat capacity of disordered Re-W alloys.

The Re(1-x)W(x) alloy is formed by continuous neutron bombardment of W, the core material making up the shield in fusion devices. Here, we present an ab initio study of the lattice dynamical properties of this commercially important alloy. The dynamical (force constant) matrix was obtained through a first-principles, density functional perturbation theory. Various vibrational properties, such as fuzzy phonon dispersion relations, density of states (DOS), scattering life-times, vibrational entropy and specific heat are studied. The effects of short-range ordering is shown to be important in the 50-50 alloy.