Development of n-body expansion interatomic potentials and its application for V

• A new formalism of the n-body interatomic potentials is developed by explicitly accounting for 3-body interactions.
• The interatomic potentials for V are constructed.
• The formalism more accurately predicts properties of V in comparison with the available potentials.

An improved accuracy in the description of base characteristics of the bcc refractory metals, including melting point and heat of fusion, with the help of atomistic simulation methods, requires further development of reliable interatomic potentials, more precisely taking into account the angle part of interactions. A new approach for the description of interactions in atomistic systems based on known n-body expansion of the total energy has been developed. The embedded atom method (EAM) ansatz is derived from this expansion within a centrally symmetric approximation. With the developed approach, the total energy is regarded consisting of a pair potential part, 3-body interactions without model considerations and a term that describes all other n-body interactions like the embedded function of EAM. As an application, accurate many-body potentials for V have been constructed. The formation energies and volumes of self-interstitials and di-vacancies are calculated. The cohesive energy, elastic constants, phonon spectra, the vacancy formation and migration energies, surface energies, the transition to a rhombohedral phase with increasing pressure, the thermal expansion, the melting point and the heat of fusion have also been studied, and satisfactory agreement with available experimental data has been found.