@unpublished{pittir22711,
           month = {September},
           title = {Vibrational Anharmonicity in the Water-Nitrate Complex, Ice, and Gas Hydrates: Applications to Spectroscopy and Thermal Transport},
          author = {Eric G. Kratz},
            year = {2014},
        keywords = {Quasi-harmonic thermal conductivity phonon infrared proton disorder},
             url = {http://d-scholarship-dev.library.pitt.edu/22711/},
        abstract = {Vibrational anharmonicity strongly influences the properties of gas-phase complexes and solids. Anharmonicity is responsible for the observation of ?forbidden? vibrational transitions, thermal expansion, and phonon-phonon scattering. In the first portion of this dissertation the vibrational spectra of [(NO3-)(H2O)] and its isotopologues are examined through effective  Hamiltonian and vibrational configuration interaction  calculations employing ab initio force constants. While a  harmonic treatment of the [(NO3-)(H2O)] infrared absorption spectrum predicts two OH stretch transitions, four strong
peaks are experimentally observed. Anharmonic vibrational calculations confirm that the ?extra? transitions are due to the rocking motion of the water molecule relative to the nitrate ion and a Fermi resonance between the OH stretch and water bend overtone. The second part of the dissertation explores the nature of the vibrational anharmonicity of gas hydrates and ice Ih as well as its effects on the structure and thermal conductivity. The
arrangement of the hydrogen atoms in the solids and the gas-water interactions are found to have a strong influence on some of the properties of the crystals. Coarse-grained simulations and analytic scattering approximations qualitatively reproduce the observed behavior of the thermal conductivity of gas hydrates and ice. In addition, the calculations reveal that guest-host coupling cannot fully explain the differences in the thermal conductivity of gas hydrates and ice.}
}