An Exact Ewald Summation Method in Theory and Practice.

We present the widespread Ewald summation method in a new light by utilizing a truncated Gaussian screening charge distribution. This choice entails an exact formalism, also as particle mesh Ewald, which in practice is not always the case when using a Gaussian screening function. The presented approach reduces the number of dependent parameters compared to a Gaussian and, for an infinite reciprocal space cutoff, makes the screening charge distribution width truly arbitrary. As such, this arbitrary variable becomes an ideal tool for computational optimization while maintaining accuracy, which is in contrast to when a Gaussian is used.