A molecular dynamics study of thorium nitride

A molecular dynamics (MD) calculation was performed for thorium nitride (ThN) in the temperature range from 300 to 2800 K to evaluate the thermophysical properties, viz. the lattice parameter (a), linear thermal expansion coefficient (αlin), compressibility (β), heat capacity (CP), and thermal conductivity (λ). A Morse-type potential function added to the Busing-Ida type potential was employed as the potential function for interatomic interactions. The interatomic potential parameters were semi-empirically determined by fitting to the experimental values of the lattice parameter with temperature. The calculated results of linear thermal expansion coefficients correspond to the experimental values. We obtained the calculated values of the compressibility of ThN, which have not been experimentally measured. In the case of the heat capacity, the lattice vibration contribution and lattice dilational contributions were evaluated, and in the case of the thermal conductivity, only the phonon contribution was evaluated by the MD calculation.