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Title: Phononic crystals of spherical particles: A tight binding approach

The vibrational dynamics of a fcc phononic crystal of spheres is studied and compared with that of a single free sphere, modelled either by a continuous homogeneous medium or by a finite cluster of atoms. For weak interaction among the spheres, the vibrational dynamics of the phononic crystal is described by shallow bands, with low degree of dispersion, corresponding to the acoustic spheroidal and torsional modes of the single sphere. The phonon displacements are therefore related to the vibrations of a sphere, as the electron wave functions in a crystal are related to the atomic wave functions in a tight binding model. Important dispersion is found for the two lowest phonon bands, which correspond to zero frequency free translation and rotation of a free sphere. Brillouin scattering spectra are calculated at some values of the exchanged wavevectors of the light, and compared with those of a single sphere. With weak interaction between particles, given the high acoustic impedance mismatch in dry systems, the density of phonon states consist of sharp bands separated by large gaps, which can be well accounted for by a single particle model. Based on the width of the frequency gaps, tunable with the particle size, andmore » on the small number of dispersive acoustic phonons, such systems may provide excellent materials for application as sound or heat filters.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. NiPS Laboratory, Dipartimento di Fisica, Università di Perugia, Via Pascoli, 06100 Perugia (Italy)
  2. CMM - Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento (Italy)
  3. (Italy)
  4. Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38123 Trento (Italy)
Publication Date:
OSTI Identifier:
22251529
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 139; Journal Issue: 17; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BRILLOUIN EFFECT; CRYSTALS; DENSITY; DISPERSIONS; FCC LATTICES; PARTICLE SIZE; PARTICLES; PHONONS; SINGLE-PARTICLE MODEL; SPECTRA; WAVE FUNCTIONS; WEAK INTERACTIONS