We propose a harmonic surface mapping algorithm (HSMA) for electrostatic pairwise sums
of an infinite number of image charges. The images are induced by point sources within a
box due to a specific boundary condition which can be non-periodic. The HSMA first
introduces an auxiliary surface such that the contribution of images outside the surface can
be approximated by the least-squares method using spherical harmonics as basis functions.
The so-called harmonic surface mapping is the procedure to transform the approximate …