Statistical models were generated with this new descriptor set following the same general workflow outlined in Figure . Intriguingly, the Boltzmann-averaged descriptor dataset provided better statistical models for thermal decomposition, while the minimum energy conformer dataset proved more effective for prediction of the impact sensitivity (vide infra). This result is consistent with the observation that many of the tetrazoles in our experimental dataset have a melting point below their decomposition temperature. Consequently, these tetrazoles have a high degree of conformational flexibility prior to decomposition, which is suitably approximated by the Boltzmann averaging of the descriptor set. However, decomposition initiated by impact occurs in the solid state, in which HEMs generally adopt a single conformation in a crystal lattice. The statistical model for Tdec derived from the Boltzmann-averaged parameters (Figure ) carries excellent statistical metrics, yielding predicted Tdec values within 30 °C of the experimental value for 90% of the 31 tetrazoles in the dataset, with an MAE of 16 °C for the 28 tetrazoles comprising the training set. The improved performance of this statistical model as compared to the model using descriptors derived from the crystal structure conformers is also attributed to the expanded set of NBO descriptors used in this second generation of modeling. This improvement is highlighted by the inclusion of the average N 1 -N 2 /N 2 -N 3 σ bond order descriptor, which was constructed to account for tetrazoles (3 out of 31) that have a double bond between N 2 and N 3 in their natural Lewis structures. Closer inspection of this descriptor reveals a correlation coefficient with the N 2 -N 3 σ bond order of 0.87, while the descriptor is not correlated with the N 1 -N 2 σ bond order (correlation coefficient = 0.04). The large positive model coefficient for the average N 1 -N 2 /N 2 -N 3 σ bond order in the MLR equation (Figure ) supports a rate-determining N 2 -N 3 bond breakage in the decomposition of both tetrazole classes. The X=X* maximum occupancy descriptor is the highest occupancy in any π* orbital within the tetrazole ring, accounting for any tetrazole resonance structures. The third descriptor in the model is the average calculated NMR shift of all 4 nitrogen atoms in the ring.