Ab initio determination of the (001) antiphase-boundary energy in the DO22 Ni3V compound

The cohesive energies of L1(2), D0(22), D0(23) and selected one-dimensional (1D) long-period structures (LPSs) based on the L1(2) structure in the Ni-V system for the Ni3V composition have been obtained by ab-initio calculations using the Vienna ab-initio simulation package. Relaxations, both external and internal with respect to the cell, are taken into account in the determination of the structural stability of the 1D LPSs. At each stage of the relaxation process the D0(22) structure is the ground state. The values of the (001) antiphase-boundary (APB) energies are obtained from the energy differences of ID LPSs with respect to either L1(2) or D0(22), with stacking of at least three L1(2) cubes along the direction perpendicular to the APB. The energy effects in the ID LPSs are described in the framework of an axial next-nearest neighbour Ising model. The values of the interaction parameters are obtained in the ideal, distorted and fully relaxed structures. The APB energies are also derived from these parameters. The results show that it is necessary to consider long-range interactions in order to obtain reliable values of the APB energies. The results show also the influence of the relaxation effects on the APB energies.