New interatomic potential for computation of mechanical and thermodynamic properties of uranium in a wide range of pressures and temperatures

Abstract

A new interatomic potential for uranium is proposed. The potential is constructed in terms of the embedded-atom method (EAM). As the reference data used for the optimization of potential functions, the values of forces, energies, and stresses obtained from ab initio computations have been employed. The potential has been applied for studies of properties of crystalline phases of uranium. It has been established that the lattice parameters of the α and Γ phases, the elastic moduli, the isochore, the room temperature isotherm, and the energies of vacancy formation are in good agreement with the available experimental data and calculated results in the framework of the density-functional theory. The potential suggested facilitates simulation of the first-order phase transitions between Γ uranium and liquid and between Γ and α uranium. The melting points of uranium at pressures of up to 80 GPa, and the temperature of the phase transition between the Γ phase and α phases, at ∼3 GPa have been determined. For the first time, atomistic simulation of the phase transition between α and Γ phases of uranium has been performed.