The Effect of Interstitial Nitrogen Addition on the Structural Properties of Supercells of NdFe12-xTix x

We investigated the effect of nitrogenation on $3 \times 3 \times 2$ supercell structures of NdFe 12-x Ti x from $x = 0.028$ to $x = 1.56$ (~0.2Ti at. % to ~12Ti at. %). We used the molecular dynamics and Boltzmann probabilities to permeate titanium into NdFe 12-x Ti x across the investigated range, before nitrogenating the minimum energy structures that resulted at each permutation step. By comparison of the nitrogenated and base structures, we found that the cohesive energy gains caused by nitrogenation are mainly due to a large asymmetry introduced into the $c$ lattice parameter and the efficacy of nitrogenation decreases with increasing titanium at. %.