Efficient Multipole Expansion: Choice of Order and Density Partitioning Techniques Abstract: Two approaches to improve the convergence of the multipole series were considered: 1) an increase in the order of expansion; 2) decomposition of the molecular charge density into smaller distributions. New decompositions of the molecular electronic density and a computational procedure to generate high-order moments are presented. The accuracy and timong of test calculations on the H₂O...H₂O system are given and suggestions are made for optimizing the choice of an expansion for more general systems.