Supplementary information for DOI: 10.1021/acs.jpcc.7b04757 POSCAR-XXX: DFT optimised structures Phonons-XXX.zip: Folders containing the force constants (FORCE_SETS), the resulting phonon frequencies (mesh.yaml), phonon partial density of states (partial_dos.dat), animations of all phonon modes (anime.ascii) e.g. to be visualized in VMD and gifs of selected phonon modes. XDATCAR-XXX: MD trajectories

This work is supported by ERC programme grant no. 277757. The authors acknowledge computing support from the UK national supercomput- ing service (Archer), via membership of the UK Mate- rials Chemistry Consortium which is funded by EPSRC (EP/L000202), and from the University of Bath computing services (Balena).