For 10 points, name these quasiparticles which correspond to the vibrational modes of a lattice.
Transport due to these entities is modelled by Peierls solution to the Boltzmann transport equation, which uses the relaxation time approximation. Klemens and Callaway name models for scattering due to these entities. Scattering of these entities in an inelastic manner increases thermal resistivity at high temperatures and is known as umklapp. For a basis of two atoms in the primitive cell, the type of these entities with a nonzero frequency at the center of the first Brillouin zone is known as their (*) optical type. Multiplying the density of states of these entities by their energy, integrating up to their cutoff frequency, and differentiating gives a temperature-cubed dependence of heat capacity at low temperatures in the Debye model. For 10 points, name these quasiparticles which correspond to the vibrational modes of a lattice.
Transport due to these entities is modelled by Peierls solution to the Boltzmann transport equation, which uses the relaxation time approximation.
phonons