The discussion clarifies that the term "quasimomentum" for phonons arises from the constraints imposed by the first Brillouin zone, which limits the wavenumber of vibrations. It establishes that the true momentum of phonons is zero, as true momentum results from translational invariance, while quasimomentum is derived from the permutational symmetry of atoms in a crystal lattice. For further understanding, refer to Ashcroft and Mermin's work, particularly the appendices that elaborate on these concepts.
PREREQUISITESStudents and researchers in solid-state physics, materials scientists, and anyone interested in the behavior of phonons in crystalline structures.
DrDu said:The momentum of phonons isn't called quasimomentum. The true momentum of phonons is 0. While the true momentum is a consequence of translational invariance, quasi- or crystal-momentum is a consequence of the permutational symmetry of the atoms in the underlying crystal. See Ashcroft and Mermin, specifically one of the appendices.