To evaluate the self-diffusion coefficient D 0 , we first carried out a 1 ns equilibration and 1 ns production simulation in the NPT ensemble, and saved 100 trajectory frames containing position and velocity information with 10 ps time resolution as initial conditions for energyconserving simulations. From each simulation snapshot, an energy-conserving simulation was propagated for 10 ps using the Verlet integrator and 1.0 fs time step to generate a trajectory of 100 frames with a 0.1 ps time interval.