Electrostatic potentials and polarization effects in proton‐molecule interactions by means of multipoles from the quantum theory of atoms in molecules

Abstract

Some atomic multipoles (charges, dipoles and quadrupoles) from the Quantum Theory of Atoms in Molecules (QTAIM) and CHELPG charges are used to investigate interactions between a proton and a molecule (F2, Cl2, BF, AlF, BeO, MgO, LiH, H2CO, NH3, PH3, BF3, and CO2). Calculations were done at the B3LYP/6‐311G(3d,3p) level. The main aspect of this work is the investigation of polarization effects over electrostatic potentials and atomic multipoles along a medium to long range of interaction distances. Large electronic charge fluxes and polarization changes are induced by a proton mainly when this positive particle approaches the least electronegative atom of diatomic heteronuclear molecules. The search for simple equations to describe polarization on electrostatic potentials from QTAIM quantities resulted in linear relations with r − 4 (r is the interaction distance) for many cases. Moreover, the contribution from atomic dipoles to these potentials is usually the most affected contribution by polarization what reinforces the need for these dipoles to a minimal description of purely electrostatic interactions. Finally, CHELPG charges provide a description of polarization effects on electrostatic potentials that is in disagreement with physical arguments for certain of these molecules. © 2012 Wiley Periodicals, Inc.

QTAIM-Based Characteristic Group Infrared Intensities of Amino Acids and Their Transference to Peptides

“…In fact, electrostatic interactions are not correctly described solely by point charge models, and the inclusion of dipolar polarization yields more realistic depictions. 12,13 In this regard, a lot of efforts have been put into developing polarizable force fields especially through quantum chemical topology (QCT) force fields. 14,15 The general idea of this theory is to use atoms from small molecules as building blocks in order to predict properties of larger molecules.…”

“…Even though this problem was reported more than 10 years ago, these force fields continue to be used ubiquitously − and even have motivated the creation of a new generation of force fields. , One of the potential reasons could be the lack of appropriate polarization to accurately describe van der Waals interactions such as London dispersion forces. In fact, electrostatic interactions are not correctly described solely by point charge models, and the inclusion of dipolar polarization yields more realistic depictions. , In this regard, a lot of efforts have been put into developing polarizable force fields especially through quantum chemical topology (QCT) force fields. , The general idea of this theory is to use atoms from small molecules as building blocks in order to predict properties of larger molecules. The theory is based on atomic transferability, the Quantum Theory of Atoms In Molecules (QTAIM) theory, , and the use of atomic multipoles.…”