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

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.