Interstitial–interstitial interactions in bcc VB group metals: Ab initiocalculations

Chemical and strain-induced interactions of oxygen and nitrogen interstitials in bcc V and Ta have been obtained for the first 12 coordination shells in the supercell first-principles calculations by the Viena ab initio simulation package (VASP). It is shown that the chemical interactions are dominating at the first several coordination shells while the strain-induced interactions become important at more distant coordination shells. The latter are in reasonable agreement with the earlier results of a microscopic phenomenological Krivoglaz–Kanzaki–Khachaturyan model (KKKM). The obtained interstitial–interstitial interactions have been used in calculations of the concentration dependence of the oxygen Snoek peak, which is in good agreement with the existing experimentaldata.

► Total, chemical and strain-induced interactions of oxygen and nitrogen interstitials in bcc V and Ta have been determined for the first 12 shells in the supercell first-principles calculations using the Viena ab-initio simulation package (VASP). These interactions exhibit very similar behaviour in all bcc metals of VB group.
► The strain-induced interactions are in reasonable agreement with those obtained earlier within the microscopic phenomenological Krivoglaz–Kanzaki–Khachaturyan model. It is shown, however, that the chemical interactions are dominating at the first several coordination shells.
► The obtained interactions have been used in calculations of the concentration and temperature dependence of the oxygen Snoek peak. The theoretical results are found to be in good agreement with the existing experimental data. The inclusion of the long-range tail of the strain-induced interactions significantly improves the description of the concentration dependence of the temperature of the Snoek maximum.