For IRMOF-10 initial optimisation was performed in the crystallographically determined spacegroup F m 3m. The resulting structure had imaginary phonon frequencies for modes corresponding to the rotation of the phenyl rings, as these degrees of freedom could not be optimised within the chosen spacegroup. Following the eigenvectors of the imaginary phonons led to a twisting of the rings, and the final structure has no imaginary phonon modes, indicating that it is a local minimum (See the phonon partial density of states in Figure in the ESI). This highlights the importance of phonon calculations to verify that the optimised structure is a true local minimum, in particular when the optimisation is restricted by symmetry. We note that displacing the structural coordinates along the phonon eigenvectors leads to a loss of crystal symmetry. The final spacegroup for the static structure is formally P 1 due to small variations in lattice vectors and atomic positions (c.f.