PHZ3400 Sound

Vibrational modes of a one-dimensional chain

Harmonic approximation: inter-atomic forces as springs

• If we put energy into a crystal the atoms will begin to vibrate.
• We are able to put energy into the crystal in two ways: Mechanical and Thermal.
  • Mechanical energy are sound waves
  • Thermal energy can be used to measure resistivity.
• Periodicity helps to simplify the problem of lattice vibrations.