PRACTICAL EXPRESSIONS FOR THE 2-CENTER MULTIPOLE EXPANSION OF R(12)(-1)

Journal article, 1995

An explicit and transparent deduction of a conventional expression for the two-center multipole expansion of the Coulomb potential, r, in terms of spherical harmonics, is perfomed. An intermediate expression in the deduction is shown to be well suited for transformation into a Cartesian representation. Practical formulas are produced that allow for safe and efficient implementations in computer programs. Electrostatic interactions between two pairs of point charges are computed and the importance to include the higher multipole interactions is stressed.