After the first initial equilibration, systems were further thermalized with a Nosé-Hoover thermostat on the ions at 300 K for several picoseconds with a coupling frequency of 1500 cm -1 before finally switching to the NVE ensemble for the production runs for at least 10 ps. Configurations were saved every 50 steps for analysis. More information about the lengths of the trajectories, time steps and energy conservation are reported in Table of the ESI †.