This work is devoted to the development of Moleculas Statics model of the diffusion features of point defects in bcc metals. In particular, the proposed model allows to calculate activation volumes which describe the influence of pressure on the diffusion processes in solids. Our model realizes a new approach that makes it possible to self-consistently determine atomic structure near vacancy and constants C characterizing the displacement of atoms in an elastic matrix around computational cell. We also take into account that the energies of a perfect system and a system with a defect depend in different ways on the outer pressure. This modifies the values of the migration and formation volumes. The effect is usually neglected in calculation although it may comprise a considerable part of the activation volume. Therefore, we take into account that the time an atom needs to jump to the vacancy covers a few oscillations in the lattice site and thus, we carry out the relaxation of only those atoms which are located in a distance less then four lattice parameters from a defect. Such a distance was chosen on the basis of the results obtained from Molecular Dynamics. The formation and migration energies and volumes were calculated for the vacancies and the interstitials in various bcc metals.

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1. Simulation of interstitial atom diffusion in fcc metals with point defects