Einstein high-temperature heat-capacity expansion (source code)

= Einstein high-temperature heat-capacity expansion
{c}
{title2=$C_V=3Nk_B[1-T_E^2/(12T^2)+O(T^{-4})]$}

Expanding the <Einstein model of a solid> internal energy gives $U=3Nk_B[T+T_E^2/(12T)+O(T^{-3})]$, because the constant term in the thermal occupation cancels the <zero-point energy>. Differentiation yields the displayed <heat capacity> and proves absence of a $1/T$ term. The ratio of the $T^{-2}$ and constant coefficients determines $T_E$ independently of sample size.