Symbol θ‎. A parameter that appears in the Debye theory of specific heat. It has the dimensions of temperature and is defined by θ‎=hν‎/k, where h is the Planck constant, ν‎ is the maximum frequency for the lattice vibrations of the solid, and k is the Boltzmann constant. The Debye temperature is characteristic of a particular material; for example, for sodium θ‎ is 150 K.