Density functional theory simulations of two-dimensional infrared spectra for hydrogen-bonded acetic acid dimers

摘要

Two-dimensional coherent infrared spectra are simulated based on density functional theory calculations to analyze vibrational couplings in hydrogen-bonded acetic acid dimers. Anharmonic sixth-order force fields covering up to three-body interactions are calculated for up to 11 normal modes. Three mechanisms for vibrational coupling within the two intermolecular hydrogen bonds are considered: anharmonic coupling of the high-frequency O-H stretching mode to low-frequency modes, Fermi resonance coupling the of O-H stretching mode to fingerprint mode combination tones, and a combination of both. Predicted coherent two-dimensional infrared spectra show distinct signatures for the different coupling mechanisms. (c) 2005 Wiley Periodicals, Inc.