Impact of Finite Phonon Lifetimes on the Spin Dynamics of Single-Molecule Magnets

The development of single-molecule magnets (SMMs) for information storage and processing relies on compounds with long spin lifetimes, and thus requires an understanding of the spin-phonon coupling. The phonon bath itself has a central role in these interactions, and hence knowledge of the impact of the intrinsic phonon lifetimes is crucial. Here we address this challenge by performing fully ab initio calculations of the phonon linewidths for a molecular crystal of a high-performance SMM. We find that the commonly assumed Born-Markov approximation is justified as phonon dynamics are orders of magnitude faster than the spin dynamics, and that employing ab initio-calculated linewidths in spin-dynamics simulations are secondary to employing a dense numerical sampling of the phonon modes in reciprocal space.