L n 3 ) are the reciprocal lattice vectors for the cubic simulation box of side length L and volume V = L 3 . The prime on the sum indicates that i = j term is excluded from the summation when n = 0. The electrostatic energy is invariant with respect to the damping parameter κ e , which we set to κ e = 5/L, where L is the side length of the cubic simulation cell. With this choice of κ e , the sum over n can be replaced by the simple periodic boundary condition for the short range (erfc term) contribution to the electrostatic energy.