Correlation functions for simple hopping among the octahedral and tetrahedral sites in a body-centered-cubic lattice

The correlation functions for one and a pair of specific particles are calculated for an ensemble of particles making nearest-neighbor simple jumps among the tetrahedral and octahedral interstitial sites in a bcc lattice. These correlation functions are used to obtain diffusion coefficients and NMR relaxation times due to $I-S$ (unlike-spin) and $I-I$ (like-spin) dipolar interactions. Our results are compared to previous theories and to existing experimental results.