  We develop a thermodynamically consistent chemo-thermo-mechanical model for
the $\beta\rightarrow\delta$ phase transition of energetic HMX crystals. In
contrast to previous models, which either considered specific heat to be a
constant or utilized a calibrated function, this model provides novel
expressions for the specific heats at constant volume and constant elastic
strains derived directly from continuum mechanics. In addition, the model
provides a novel prediction for the critical temperature at which the chemical
heating rate achieves its extremum for Arrhenius kinetics. The numerical
solution predicts highly nonlinear specific heat behavior including order of
magnitude changes.
