Deriving Static Atomic Multipoles from the Electrostatic Potential

The
description of molecular systems using multipolar electrostatics calls
for automated methods to fit the necessary parameters. In this paper,
we describe an open-source software package that allows fitting atomic
multipoles (MTPs) from the ab initio electrostatic potential by adequate
atom typing and judicious assignment of the local axis system. By
enabling the simultaneous fit of several molecules and/or conformations,
the package addresses issues of parameter transferability and lack
of sampling for buried atoms. We illustrate the method by studying
a series of small alcohol molecules, as well as various conformations
of protonated butylamine.