AAPT Abstract Archive

Abstract Information

  Session: Tools to Support the Conceptual Understanding of Magnetism and Quantum Mechanics
  Paper Type: Contributed
  Title: The Effects of van Hove Singularities on Intrinsically Localized Vibrations
  Meeting: 2017 Winter Meeting: Atlanta, Georgia
  Location: N/A
  Time: 3:20PM
  Author: Benjamin A. Agyare,, Stockton University,
6096263516, Benjamin.Agyare@stockton.edu
  Co-Author(s): Peter S. Riseborough,
  Abstract: 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.
  Footnotes: None
  Presentation: Presentation at AAPT Winter Conference in Atlanta.pptx

2003 © American Association of Physics Teachers
Have questions about this site? Email the webmaster.
AAPT Home AAPT Abstract Archive Past Meeting Info