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<p>We build on results from our previous investigation into ice Ih using a combination of
classical many-body molecular dynamics (MB-MD) and normal mode (NM) calculations to obtain molecular level information on the spectroscopic signatures in the OH
stretching region for all seven of the known ordered crystalline ice phases. The classical
MB-MD spectra are shown to capture the important spectral features by comparing
with experimental Raman spectra. This motivates the use of the classical simulations
in understanding the spectral features of the various ordered ice phases in molecular
terms. This is achieved through NM analysis to first demonstrate that the MB-MD
spectra can be well recovered through the transition dipole moments and polarizability
tensors calculated from each NM. From the normal mode calculations, measures of the
amount of symmetric and antisymmetric stretching are calculated for each ice, as well
as an approximation of how localized each mode is. These metrics aid in viewing the
ice phases on a continuous spectrum determined by their density. As in ice Ih, it is
found that most of the other ordered ice phases have highly delocalized modes and
their spectral features cannot, in general, be described in terms of molecular normal
modes. The lone exception is ice VIII, the densest crystalline ice phase. Despite being
found only at high pressure, the symmetry index shows a clear separation of symmetric
and antisymmetric stretching modes giving rise to two distinct features.
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VIBRATIONAL MODES IN SMALL Agn, Aun CLUSTERS: A FIRST PRINCIPLE CALCULATION
