Comparison of thermodynamic derivative quantities from ab initio reactive Monte Carlo simulations and thermochemical calculations of PETN products*

In a previous publication (R. B. Jadrich et al., J. Chem. Phys. 154, 244307, 2021), we outlined the methodology for performing a first-principles reactive Monte Carlo simulation of PETN products using density functional theory (DFT). This method foregoes the deterministic nature of molecular dynamics in exchange for stochastic Monte Carlo moves that allow for rapid chemical equilibration. Therein we compared the energies, pressures, and Chapman-Jouguet states of DFT with thermochemical calculations and found generally good agreement. Here, we extend this work to compare the values of thermodynamic derivatives such as heat capacities and the Grüneisen parameter, between the first-principles reactive Monte Carlo and thermochemical equations of state. The implications of this work for thermochemical EOS in general and the development of new analytical models, such as the addition of thermal models to the MACAW EOS (E. Lozano and T. D. Aslam, J. Appl. Phys. 131, 015902, 2022.) will be discussed.