Benchmark calculations and error cancelations for bond dissociation enthalpies of X–NO2

Abstract

Safety plays an important role in determining the applicability of energetic compounds, and the bond dissociation enthalpy (BDE) of the “trigger bond” X-NO2 provides useful information to evaluate various safety properties. Accurate and rapid calculation of the BDE of X-NO2 is of great significance to perform the high-throughput design of energetic compounds, which becomes an increasingly popular means of materials design. We conduct a benchmark BDE calculation for 44 X-NO2 samples extracted from the iBond database, with the accuracies of 55 quantum chemistry calculation levels evaluated by the experimentally measured values. Only four levels have the global mean-absolute deviation (MAD) less than 10 kJ/mol, but no calculation level can achieve that all the local MADs of each category less than 10 kJ/mol. We propose a simple correction strategy for the original calculation deviations, and apply it to 30 calculation levels screened out through a series of accuracy assessments and obtain the corrected MAD <6 kJ/mol in some cases. We define a normalized time-cost (NTC) to evaluate the time-cost of each calculation level, and confirm that PBE0-D3/6-31G∗∗ (MAD = 6.4 kJ/mol, NTC = 0.8) works the best for most cases, followed by M062X/6-31g∗∗, M062X/6-311g∗∗ and ɷB97XD/6-311g∗∗, based on an insight into the accuracy-cost trade. The present work provides an accurate and fast solution for calculating X-NO2 BDE via quantum chemical methods, and is expected to be beneficial to enhance the safety prediction efficiency of energetic compounds.