Question
This model establishes a cutoff frequency equal to speed of sound times the radius of a sphere with the same volume as the Brillouin (“bree-WANN”) zone. For 10 points each:
[10e] Name this model in which heat capacity goes with the cube of temperature at low temperatures, unlike the Einstein model, which incorrectly predicts exponential temperature dependence.
ANSWER: Debye model [or Debye approximation]
[10m] The Einstein model behaves badly at low temperature because it does not account for the presence of these quasiparticles whose branch of the dispersion curve goes to zero at zero wavenumber.
ANSWER: acoustic phonons [prompt on phonons]
[10h] The Debye approximation can be used to calculate deformation potentials that describe an interaction between electrons and acoustic phonons with this property. An interaction between electrons and optical phonons with this property in polar semiconductors is named for Herbert Fröhlich.
ANSWER: longitudinal [accept longitudinal acoustic phonons or longitudinal optical phonons; prompt on LA phonons or LO phonons]
<Arya Karthik, Physics>
Summary
| 2023 Chicago Open | 08/05/2023 | Y | 1 | 0.00 | 0% | 0% | 0% |
Data
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