Nonbonded potential function models for crystalline oxohydrocarbons

Abstract

Nonbonded O...O potential parameters of the (exp - 6) type were derived from five selected oxohydrocarbon crystal structures, which do not have hydrogen bonds: β-oxygen, carbon dioxide (CO2), trioxane (C3H6O3), tetroxocane (C4H8O4) and succinic anhydride (C4H4O3). Previously established hydrocarbon H and C nonbonded parameters were transferred. Net atomic charges were calculated separately by obtaining a least-squares fit to the molecular electric field calculated by the ab initio self-consistent-field molecular-orbital method. The resulting O...O nonbonded potential was found to transfer well to the structures of pentoxecane (C5H10O5), 1,4- cyclohexanedione (C6H8O2) and diglycolic anhydride (C4H4O4). The potential did not transfer well to the structures of p-benzoquinone (C6H4O2) and furan (C4H4O). The addition of an approximate weak hydrogen-bonding potential for a C-H... O hydrogen bond improved the fit to the latter two structures.