Polyparametric modification equation for estimating thermodynamic properties of energetic nitro compounds

Calculation methods, based on hybrid density-functional theory with the basis sets of B3LYP/ 6-311+G (2d, p)//B3LYP/6-31G(d, p)and B3LYP/6-31+G(d)//B3LYP/6-31G(d, p), were applied to determine the thermodynamic characteristics of various energetic nitro compounds. A parametric modification equation and the least-squares approach were used to identify 21 of the energetic research compounds. The atomization energies of these 21 compounds have an average relative error of 0.21–0.25% of the experimental values. The enthalpy (H _f) and the Gibbs energy (G _f) of formation have mean absolute errors of 10.8–11.4 kJ/ mol (2.6–2.7 kcal/mol) and 10.0–10.3 kJ/mol (2.4 kcal/ mol), respectively. The enthalpy and the Gibbs energy of formation obtained exceed those in the literature obtained by semiempirical calculations. The calibrated least-squares parameters and parametric equations were used to predict H _f and G _f for the five newly developed energetic nitro compounds for further applications.Acknowledgements. The authors would like to thank the National Science Council of the Republic of China for financial support of this work under grant no. NSC-91-2113-M-014-003. The National Center for High-Performance Computing providing the computation facility is also acknowledged.