We present a microscopic description of the vibrational spectroscopy of the OH stretch of HOD in liquid D2O. Our model predicts that OH frequency correlations decay with a sharp and rapid (≈35 fs) decrease, followed by a beat at ≈125 fs from intermolecular oxygen vibrations. On a short time scale (≈200 fs), ultrafast infrared spectroscopy of the OH stretch is sensitive to localized intermolecular motions. For times longer than ≈200 fs, cooperative molecular rearrangements drive dephasing. The interplay of electric field fluctuations, both local and cooperative, dictate vibrational frequency shifts and destroy vibrational coherence in water.
Eaves, J. D., Tokmakoff, A. and Geissler, P. L. Electric field fluctuations drive vibrational dephasing in water. J. Phys. Chem. A 109, 9424 (2005)