  We apply the Poisson sum rule to obtain formal expressions for the Fourier
coefficients of the potential of a lattice of generalized charge. Each
generalized charge is assumed to contribute to the potential a term which
depends only on the vector displacement from the charge's location. The
coefficients are explicitly calculated for Coulomb and Yukawa-type individual
particle potentials. The potentials of finite and disordered lattices are also
briefly considered.
