Vibrational spectroscopy of water in the bulk and at the liquid/vapor interface

Water and the unique properties it possesses are crucial in science and nature. This thesis deals primarily with theoretical analysis of the vibrational spectroscopy of water in the liquid phase. The OH stretch frequency is very sensitive to the local hydrogen bonding environment and hence is an excellent probe of both structure and dynamics of water. To maximize the information that can be obtained from experimental spectroscopic studies in the condensed phase complementary theoretical work is very useful.;In order to calculate vibrational spectroscopy in the condensed phase one needs to be able to relate a vibrational chromophore's instantaneous frequency to the surrounding solvent structure in a molecular dynamics simulation. In a neat fluid the vibrational chromophores may also be coupled, making the vibrational excitation delocalized over many molecules, which complicates the problem.;The first part of this thesis is concerned with improving on methods developed to calculate Raman, infrared, and sum frequency generation spectra of dilute HOD in D2O. Here the OH stretch is uncoupled from the OD stretches and acts as a probe of its local environment. An improvement on a previous method referred to as the electronic structure/molecular dynamics method is presented. Then the spectroscopy is related to the hydrogen bonding in the bulk and at liquid/vapor interface.;Next we develop an approximate method to calculate the line shape for a system of coupled vibrational chromophores, which we call the time averaging approximation (TAA). This method is easier to apply than the exact method for a large number of coupled chromophores and works well on model systems. The TAA is then applied to the problem of neat H2O. We are able to assess the effect of the coupling in this problem and the implications for the interpretation of the experimental spectra.