As mentioned above the empirical heat capacity curve for silver seems to be proportional to T² or T³ for small values of T. The graph of the quantum mechanical heat capacity function derived above indicates that for values of T near zero the heat capacity function is zero and flat.
To investigate the behavior of the heat capacity function for small T it simplify matters let hω/k, which has the dimensions of temperature,
be denoted as θ. This parameter is somethimes called the Einstein temperature because it was Einstein who first formulated this line of analysis. (Einstein was far more adept at realizing the implications of the quantization of energy found by Planck than Planck himself.)