Hydrogen Bonding in the Methanol Dimer

Correct evaluation of hydrogen bonding is critical to theoretical determination of carbohydrate structure, and accurate criteria are necessary for identification of hydrogen bonds in crystal structures. In this work, two methanol molecules are used as models for different possible hydroxyl groups in carbohydrate materials such as cellulose. The present work calculates energy as a function of both hydrogen bond length and angle over wide ranges, using quantum mechanics (QM). The QM wavefunctions are analyzed in terms of R. F. W. Bader's Atoms-In-Molecules theory. Bond Critical Points and bond paths, indicators of bond formation, can be found over distances from 1.5 to 3.5 A, and other indicators such as atomic charge and atomic volume differences diminish at somewhat shorter distances.