Partial charges for molecular-mechanical models of heterocyclic compounds: pyridine nitrogen.

This paper deals with the effect of introducing an additional interaction site onto molecular-mechanical models of nitrogen-containing heterocyclic compounds. The introduction of only one additional site next to nitrogen atoms is shown to result in significant improvement of the quality of the models along with negligible slowdown of calculation speed. Concretely, it was proposed to introduce the site inside the aromatic ring at a distance of 0.4 Å from the nitrogen atom center. All the parametrization can be completely automated. The proposed force field allows predicting heats of evaporation of liquids of the compound under investigation with an accuracy of 1 kcal/mol.