where ω 0 = 3745 cm -1 and ∆ = 160.5 cm -1 /(V/ Å). Using this expression, the vibrational spectra of water is be constructed as histograms of the field along OH bonds. This approach assumes that each OH bond behaves as an independent oscillator, neglecting vibrational coupling between OH bonds, an assumption that is nearly exact for dilute HOD in D 2 O but an approximation for pure H 2 O. It also assumed that the spectra is purely inhomogeneously broadened. Nevertheless, it has been successfully employed to study multiple forms of vibrational spectroscopy in water.