Motion-induced NMR spin relaxation times in the low-temperature high-frequency limit

We point out that some commonly used expressions for NMR relaxation times $T_1$ and $T_{1\rho }$ for motion-induced dipolar spin relaxation are in error at sufficiently low temperatures or high frequencies. Correct expressions are presented for simple hopping via the vacancy mechanism in simple-cubic and face-centered-cubic lattices and via the anion-interstitialcy mechanism in a fluorite lattice.