Crystal momentum

The quasi-momentum has nothing to do with the classical momentum of a moving mass, but is the amount included in the momentum conservation laws with the ( wave-like ) quasiparticles such as phonons or magnons.

Phonons, for example, are elastic vibrations of the atoms around their equilibrium position in a crystal lattice; because oscillate at a fixed time all the atoms in different directions, the crystal has no pulse as a whole.

The quasi-momentum of a wave can be calculated by the de Broglie relation of the wave vector:

With the reduced Planck 's constant

• Quantum physics
• Solid State Physics