A well-behaved electrostatic potential based method using charge restraints for deriving atomic charges: the RESP model

TLDR: In this paper, the authors present an approach to generate electrostatic potential (ESP) derived charges for molecules, which optimally reproduce the intermolecular interaction properties of molecules with a simple two-body additive potential, provided that a suitably accurate level of quantum mechanical calculation is used to derive the ESP around the molecule.

Abstract: We present a new approach to generating electrostatic potential (ESP) derived charges for molecules. The major strength of electrostatic potential derived charges is that they optimally reproduce the intermolecular interaction properties of molecules with a simple two-body additive potential, provided, of course, that a suitably accurate level of quantum mechanical calculation is used to derive the ESP around the molecule. Previously, the major weaknesses of these charges have been that they were not easily transferable between common functional groups in related molecules, they have often been conformationally dependent, and the large charges that frequently occur can be problematic for simulating intramolecular interactions