As for the single-phonon Orbach rates, we observe that the dependence on the fixed linewidth becomes smaller with improved reciprocal-space integration (the rates for Γ = 0.1 cm -1 and Γ = 10 cm -1 differ by a factor of 1.8 at 60 K for the 2×2×2 grid, which reduces to 1.3 for the 5×5×5 grid), and they appear to converge to the experimental values. We also note that the increased sensitivity of the magnetic relaxation rates in the Raman region towards choice of phonon linewidth compared to the Orbach region could provide an explanation for the increase in the distribution of magnetic relaxation rates for this compound as the temperature is decreased; i.e. the presence of crystalline disorder, shown to the correlate with the width of the distributions of magnetic relaxation rates, has more of an effect on the Raman rates, which tend to dominate as temperature is reduced. Calculations are performed using the solid-state phonon modes on 5×5×5 q-point grid,