Session:
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Tools to Support the Conceptual Understanding of Magnetism and Quantum Mechanics
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Paper Type:
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Contributed
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Title:
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The Effects of van Hove Singularities on Intrinsically Localized Vibrations
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Meeting:
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2017 Winter Meeting: Atlanta, Georgia |
Location:
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N/A |
Date:
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Time:
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3:20PM
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Author:
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Benjamin A. Agyare,, Stockton University,
6096263516, Benjamin.Agyare@stockton.edu
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Co-Author(s):
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Peter S. Riseborough,
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Abstract:
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Intrinsically Localized Modes (ILMs) have purportedly been observed in NaI but only for wave-vectors, q at the corner of the 3-D Brillouin Zone. It has been suggested that, for high-symmetry q vectors, several van Hove singularities may converge at one frequency producing a large peak in the two-phonon density of state and giving rise to ILMs with these q values. We fit the experimentally determined acoustic and the optic phonon modes using a nearest neighbor and a next-nearest neighbor force constant. We find that the two-phonon density of states, for fixed q exhibits non-divergent van Hove singularities. The frequencies of these features are found to vary as q is varied. We intend to search for q values at which the two-phonon density of states is enhanced and then examine whether the anharmonic interactions can bind the two-phonon excitations to produce a quantized ILM.
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Footnotes:
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None
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Presentation:
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Presentation at AAPT Winter Conference in Atlanta.pptx
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