An animation showing the movement of the CEC that qualitatively demonstrates the dynamic nature of the GCs is provided in the Supporting Information. The animation shows the positions of the oxygen atoms associated with the CEC as a function of time, with a history showing the positions of the CEC over the previous 125 fs. The simulation is for the c96C system at 800 K and shows 9 ps from a 125 ps simulation. The trajectory traced out over the entire simulation is shown in light blue. The CEC positions over the past 125 fs are shown in dark blue.