sentences:  For small molecules one may wish to use additional sites at the centers of bonds; for larger molecules one may use a single site to describe a group of atoms such as a methyl group.The DMA procedure is exact and very fast, but for modern large basis sets with diffuse basis functions it has to be modified somewhat.When the basis functions have exponents that are small, the product function extends over several atoms, and it is better to calculate the distributed multipoles by numerical quadrature over a grid of points.