三硝基甲烷键离解能和生成焓的理论计算

采用密度泛函(DFT)四种交换/相关函数(B3LYP、B3P86、B3PW91和PBE0)结合不同的基函数,求得了三硝基甲烷C-NO2键的离解能(BDE),并且通过合理选择参考物硝基甲烷,设计等键等电子对反应,计算了气相三硝基甲烷分子的生成焓(HOF).与实验数据进行比较,PBE0/6-31g*计算出的BDE值最好,误差为-2.1 kcal mol-1;PBE0密度泛函结合带极化函数的6-31g基组得到的HOF值与实验值吻合的最好(误差在0.1 kcal mol-1以内).

Theoretical calculation of bond dissociation energy and enthalpy of formation for trinitromethane

The bond dissociation energy(BDE) of C-NO_2 for trinitromethane was calculated using four exchange/correlation functionals(B3LYP,B3P86,B3PW91 and PBE0) of density functional theory(DFT) in combination with different basis sets.The enthalpy of formation(HOF) of trinitromethane in the gas was also computed by choosing suitable reference compound CH_3NO_2 and designing isodesmic and isogyric reaction.Compared with the corresponding experimental value,the PBE0/6-31G* can give the best result,with a deviation of-2.1 kcal mol~-1.For the enthalpy of formation,levels of theory employing PBE0 functional with 6-31G basis sets,augmented with polarization functions,were found to be in the best agreement with the experimental result,with a deviation within 0.1 kcal mol~-1.