Towards improved force fields: III. Polarization through modified atomic charges

A method of modeling polarization by representing an atomic-centered induce d dipole as a set of induced charges on the atom and its immediate neighbor s is presented. The method is based on earlier work on deriving atomic char ges from a distributed multipole analysis (P. J. Winn et al., J Phys Chem A 1997, 101, 5437; G. G. Ferenczy, J Comput Chem 1991, 12, 913). The method has been applied to the water dimer, water trimers, formaldehyde-water comp lexes, methanol complexes, and DNA basepairs. It was found that the induced charges described the various cooperative and anticooperative hydrogen bon ding systems well, both qualitatively and quantitatively (as compared with Hartree-Fock calculations). Importantly, it has been shown that, when an in duced charge (or induced dipole) model is used for larger molecules, a corr ection term is required for the underlying electrostatics. (C) 1999 John Wi ley & Sons, Inc. J Comput Chem 20: 704-712, 1999.