Novel point charge models: reliable instruments for molecular electrostatics

A novel method to compute atomic charge distribution is proposed. The start ing data for the computation are the topology of a molecule and electronega tivities of either constituent atoms or atomic orbitals. The topology of a molecule is represented by a molecular graph or, in a more advanced model, by an orbital graph that reflects an orbital constitution of atoms. The dis tinctive feature of the method is that the starting atomic (orbital) electr onegativities equilibrate in the same fashion that electrical potentials do in the nodes of a closed electrical network. Thus, the well-developed form alism of the theory of electrical circuits was applied for computation of p artial atomic charges. In addition, the problem of parametrization of halog ens was solved using a specially developed procedures. Comparison of the ob tained charges with those produced by means of various computational scheme s [Partial Equalization of Orbital Electronegativities (PEOE), Mulliken pop ulation analysis, natural population analysis, Bader's AIM, method of gener alized atomic polar tensors (GAPT) and an electrostatic potential-based met hod, CHELPG] and with some molecular spectral characteristics proves that b oth models, but especially the orbital graph charge model, provide fast, co nvenient and reliable methods to calculate theoretically justifiable atomic charges for a variety of chemical species. The developed charge models are well suited for application in many areas of molecular modeling and QSAR/Q SPR studies. Copyright (C) 2001 John Wiley & Sons, Ltd.