Single-molecule magnets (SMMs) have been actively studied for their potential applications as a new generation of data storage materials. Chemical qubits are of intense interest for quantum computing. For SMMs, each molecule behaves as a magnet with a barrier for spin reversal. Heights of the barriers and spin-phonon couplings, leading to magnetic relaxation, are critical to the performance of SMMs. Spin-phonon couplings also play an important role in qubits.