Interaction Energy and the Shift in OH Stretch Frequency on Hydrogen Bonding for the H2O→H2O, CH3OH→H2O, and H2O→CH3OH dimers

The ability to use calculated OH frequencies to assign experimentally observed peaks in hydrogen bonded system hinges on the accuracy of the calculation. Here we test the ability of several commonly employed model chemistries-HF, MP2, and several density functionals paired with the 6-31+G(d) and 6-311++G(d,p) basis sets-to calculate the interaction energy (D-c) and shift in OH stretch fundamental frequency on dimerization (delta(nu)) for the H2O -> H2O, CH3OH -> H2O, and H2O -> CH3OH dimers (where for X -> Y, X is the hydrogen bond donor and Y the acceptor). We quantify the error in D-e and delta(nu) by comparison to experiment and high level calculation and, using a simple mode, evaluate how error in D-e propagates to delta(nu). We find that B3LYP and MPWB1K perform best of the density functional methods studied, that their accuracy in calculating delta(nu) is approximate to 30-50 cm(-1) and that correcting for error in D-c does little to heighten agreement between the calculated and experimental delta(nu). Accuracy of calculated delta(nu) is also shown to vary as a function of hydrogen bond donor; while the PBE and TPSS functionals perform best in the calculation of delta(nu) for the CH3OH -> H2O dimer their performance is relatively poor in describing H2O -> H2O and H2O -> CH3OH. (C) 2009 Wiley Periodicals, Inc. J Comput Chem 31; 963-972, 2010