Accurate molecular electrostatic potentials based on modified PRDDO/M wave functions:: III.: Extension of the PESP method for calculation of electrostatic potential-derived atomic charges to compounds containing Li+, Na+, Mg2+, K+, Ca2+, Zn2+, and I

The PESP (Parameterized ElectroStatic Potential) method for calculating molecular electrostatic potentials, previously parameterized for H, C, N, O, F, P, S, Cl, and Br, is extended to molecules containing Li+, Na+, Mg2+ K+, Ca2+, Zn2+, and I. For a collection of 166 molecules containing 1668 atoms with at least one metal or iodine atom, PESP achieves an average absolute deviation in electrostatic potential-derived atomic charges of 0.042e(-) compared with ab initio MP2/6-31G** calculations, with a correlation coefficient of 0.996. For a larger data set, consisting of 311 molecules encompassing all of the 16 elements just Listed (2488 total atoms), PESP achieves an average absolute deviation of 0.040e(-) and a correlation coefficient of 0.995. PESP calculations are an order of magnitude faster than the simplest nb initio method (STO-3G) on large molecules, while achieving a level of accuracy that rivals much more elaborate nb initio methods. (C) 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1456-1469, 1998.