To calculate the spin-phonon coupling, we have used two methods as implemented in our spinphonon-suite code (version 1.0.0). 49 Approach 1: finite supercell expansions. The set of phonon wavevectors q on a Γ-centred q-point sampling grid with q1×q2×q3 subdivisions are commensurate with a q1×q2×q3 supercell expansion in real space (i.e. the supercell is of the correct size to contain an integer number of phonon wavelengths for all the q on the sampling grid). For a given q-point grid, we build the required q1×q2×q3 supercell, redefined by translation to position a single molecule of 1 in the centre. The electrostatic potential of the supercell is accounted for by assigning the remaining atoms (excluding the central molecule)