A simple model for calculating atomic charges in molecules

Abstract

We propose a new atomic-charge analysis, termed adjusted charge partitioning (ACP) scheme. To partition the molecular electronic density into atomic components, weighting factors c_Ar²ⁿ⁻²exp(−α_Ar) with atomic parameters c_A and α_A are used. Extensive numerical tests were performed for 540 molecules containing 17 main-group elements H, Li to F, Na to Cl, Br, and I. The estimated dipole moments and atomic charges are compared with the data provided by a large number of alternative atomic-charge schemes including the Mulliken, Löwdin, Hirshfeld, Hirshfeld Iterative, CM5, ESP, NPA, and QTAIM population analyses. These tests show that the resulting atomic charges are insensitive to basis sets used, chemically consistent and accurately reproduce experimental dipole moments.