Atomistic simulation of the lattice constants and lattice vibrations in RCo2 and Nd1− x R x Co2 (R = rare earth)

The lattice parameters and phase stability of RCo2 and Nd1−x R x Co2 (R = rare earth) are evaluated by using interatomic pair potentials based on Chen's lattice inversion method. The calculated results demonstrate that the concentration dependence of a approximately follows Vegard's law by a = xa 1 + (1−x)a 0, where a 0 and a 1 are the lattice constants of NdCo2 and RCo2. The results are in good agreement with experiments. The properties related to lattice vibration, such as phonon density of states, specific heat and vibrational entropy, are also evaluated. The method utilized in the present investigation offers a rather easy and direct way to study the structural and vibrational properties of rare earth compounds.