On the accurate calculation of the dielectric constant from molecular dynamics simulations: The case of SPC/E and SWM4-DP water

The effect of the applied trajectory length on the convergence of the static dielectric constant was examined for the SPC/E water model with different system sizes. Very long simulation times of 6–8 ns were employed in order to track the convergence of this property. Temperature dependence and isotope effects were also investigated. A simulation for the polarizable SWM4-DP model was also carried out to compare the effect of different potential models. It is clearly shown that trajectories shorter than about 6 ns are not sufficient for a sufficiently accurate determination of the dielectric constant of these water models.