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ABSTRACT:This investigation uses the Gaussian 98 program, density functional theory (DFT) B3LYP/6-31G(d,p), and ab initio MP2/6-31G(d,p) and HF/6-31G(d) methods to model energetic diguanidinium 5,5Ј-azotetrazolate (GZT) ionic species in order to determine their decomposition mechanisms. GZT was initially cracked into two guanidinium cations (G ϩ ) and a 5,5Ј-azotetrazolate anion (ZT 2Ϫ ). Three routes-the elimination of a hydronium ion (H ϩ ), the elimination of a hydrogen radical (H⅐), and the elimination of an amine radical (⅐NH 2 )-are suggested for the decomposition of the G ϩ cation, and three routessingle ring opening, double ring opening and NON bond cleavage outside the ring-are proposed for the further decomposition of the ZT 2Ϫ anion. Fourteen decomposition species were obtained on splitting both the cation and anion. This result reveals the reliability of the aforementioned decomposition mechanisms. The transition state species were also obtained using a two-structure or three-structure synchronous transit-guided quasi-Newton (STQN) between the Cartesian coordinates of related particles at specific decomposition stages in this research. The corresponding activation energies in all decomposition stages were considered to infer the most feasible pathways of GZT decomposition.

The hybrid density-functional theory (DFT) calculated energies of C1−C16 straight-chain alkanes were obtained based on B3LYP/6-311++G(3df,2pd) single-point energies and the related thermal corrections of B3LYP/6-31G(d,p) optimized geometries. A 3-parameter modification equation and the least-squares approach are adopted to calibrate all the molecular calculated energies to produce accurate enthalpies of formation (ΔH f) and Gibbs free energies of formation (ΔG f), respectively. This study found that all compounds had 0.04% average relative error (A.R.E.) for the atomization energies, with a mean value of absolute error (M.A.E.) of just 1.1 kJ/mol for the ΔH f and 1.9 kJ/mol for the ΔG f of formation. The ΔH f values obtained in this work are superior to the improved G3(MP2)//B3LYP calculations for the same 16 alkanes in pertinent literature.

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