A computational investigation of the azide radical formation from two N₂ molecules was carried out employing the CASSCF and MRCI electronic structure methods. Potential energy curves were built considering various electronic excited states along proposed reaction coordinates. Reaction paths with C_2v and C_s symmetries were considered and energy barriers were estimated, as well as intersections between key electronic states were found. A possible reaction mechanism is suggested involving a nitrogen atom abstraction to produce linear N₃. The distinction between N₃ formed by UV radiated ices and other sources of energy is presented and rationalized. Among other results, we predict that the N₃ radical can react barrierlessly with N(²D) atoms, yielding N₂ + N₂ products.

中文翻译：

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辐射固氮中N3的形成机理：包括激发电子态的计算预测

使用CASSCF和MRCI电子结构方法对由两个N ₂分子形成的叠氮基自由基进行了计算研究。考虑沿提议的反应坐标的各种电子激发态，建立了势能曲线。考虑了具有C _2v和C _s对称性的反应路径，并估计了能垒，以及发现了关键电子态之间的交点。建议一种可能的反应机理，其中涉及一个氮原子的提取以生成线性N ₃。介绍并合理化了由紫外线辐射的冰形成的N ₃与其他能源的区别。除其他结果外，我们预测N ₃自由基可以与N（² D）原子无障碍反应，生成N ₂ + N ₂产物。