We are grateful for support from the EPSRC Centre for Doctoral training, Theory and Modelling in Chemical Sciences, under grant EP/L015722/1. We acknowledge the use of the IRIDIS High Performance Computing Facility, and associated support services at the University of Southampton. We also acknowledge the ARCHER UK National Supercomputing Service which was accessed via the UK's HPC Materials Chemistry Consortium membership, which is funded by the EPSRC (EP/L000202).