Hexagonal Lattice Phonons

Phonon dispersion on honeycomb lattice — acoustic vs. optical branches

Lattice Parameters

Optical (high freq)
Acoustic (low freq)

Honeycomb = 2-atom basis.
K-point: Dirac cone for
equal masses (graphene).

Gap opens when M₁ ≠ M₂.
Click lattice to excite mode.