An Alternative to Ewald Sums, Part 2: The Coulomb Potential in a Periodic System

Abstract The formulae for the Coulomb potential derived in this paper apply to the situation most commonly encountered in applications: a basic cell containing N charges and their periodic images. The Coulomb energy or the Coulomb forces can then be calculated using e.g., Ewald sums. The formulae given here have several advantages over the Ewald technique, in particular when N is large.