基态和单态第一激发态的联氨单分子分解反应的密度泛函研究

本文运用密度泛函B3LYP/6-311+G(3df,2p)方法研究了联氨分子的电子结构和能量，并系统分析了联氨分子的分解反应，计算绘制了单分子联氨在基态和单态第一激发态下沿N-N分解反应的势能曲线。本文计算发现联氨分子在这两种电子态下的离解能分别是：基态58.8 kcal/mol，单态第一激发态495.5 kcal/mol。基态分子分解反应是吸热反应，而单态第一激发态分解反应是放热反应。计算发现单态第一激发态的激发能是554.2 kcal/mol。结合这两种电子态下联氨分子的红外振动频率分析，本文认为，在非强制断键的情况下，联氨分子沿N-N键均裂而生成两个NH2自由基的可能性很小。

DFT Study of the Decomposition of the Ground and First Excited Singlet State of Hydrazine

This paper has calculated the electronic structure of individual molecule of hydrazine in the gas phase by means of density functional theory and considered their dissociation pathways. The optimized potential energy curves for the unimolecular decomposition of the ground and first excited singlet states of hydrazine through the N-N bond dissociation pathway are calculated. The computational method predicts the bond dissociation energy of the ground and first excited singlet states of hydrazine through the N-N is equal to 58.8kcal/mol and 495.5kcal/mol respectively. The decomposition reaction is endothermic reaction for the ground state of hydrazine, but it is exothermic reaction for the first excited singlet state of hydrazine. The excited energy is equal to 554.2kcal/mol for the first excited singlet state. With analyzing the change in normal vibrational modes from the ground state to the first excited singlet state, we considered that it has little opportunity for dissociating the hydrazine starting with the cleavage of the N-N bond to yield NH2 radicals.