513.001 Molecular and Solid State Physics

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Physical
Constants

Periodic System
of Elements

      

Phonon dispersion

Often at an oral exam I pick a material like ZnO or BaTiO3 and ask what you can tell me about the phonon dispersion. There will always be three acoustic modes. The number of optical modes depends on the number of atoms in the unit cell. I might ask you how to determine the speed of sound from the dispersion curves. You should be able to explain what Brillouin zones have to do with phonon dispersion. You should be able to explain how the phonon density of states can be calculated from the phonon dispersion and how the specific heat can be calculated from the density of states.