Extended Ewald Summation Technique
  We present a technique to efficiently compute long-range interactions in systems with periodic boundary conditions. We extend the well-known Ewald method by using a linear combination of screening Gaussian charge distributions instead of only one as in the standard Ewald scheme. The combined simplicity and efficiency of our method is demonstrated, and the scheme is readily applicable to large-scale periodic simulations, classical as well as quantum. 
Ilkka Kyl\"anp\"a\"a and Esa R\"as\"anen
physics.comp-ph