六硝基六氮杂异伍兹烷结构和性质的理论研究

用abinitio和DFT方法，分别在HF/6-31G^*和B3LYP/6-31G^*水平下全优化计算了高能量密度材料六硝基六氮杂异伍兹烷(HNIW)的α(γ)，β和ε型构象的分子几何构型、电子结构、IR谱和298～1000K温度下的热力学性质，细致分析比较了两种方法和相关的实验结果。理论计算几何参数与实验值相一致。分子中N—N键较长，N—N键Mulliken集居数较小，预示该键为热解和起爆的引发键。所得的IR谱形符合实验、指纹区频率与实验的平均绝对差值小于45cm^-1。由前线MO能级及其差值预示的热力学稳定性次序ε＞α(γ)＞β]与实验排序相吻合。

Theoretical studies on the structures and properties of hexanitrohexaazaisowurtzitane

The molecular geometries, electronic structures, IR spectra and thermodynamic properties in 298～1000K range of α(γ), β, and ε- conformations of hexanitrohexaazaisowurtzitane (HNIW) have been calculated using ab initio and density functional theory (DFT) methods at HF/6-31G^* and B3LYP/6-31G^* level, respectively. The results obtained from the two methods have been carefully compared with each other and with the experimental data. The optimized parameters of geometry are in good accordance with the experimental values. Compared with the other bonds in HNIW, the bond lengths of N- N- are longer and Mulliken population of N-N is smaller, which means that the N-N may be the initial bondin pyrolysis and explosion. The obtained IR spectra are also in good accordance with the experimental results and the average absorlute difference is less than 45cm^-1. The thermodynamic stability order ε>α(γ)>β] predicted from frontier molecular orbital energies and their gaps is the same as that measured from experiments.