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本文使用带有解析梯度的MCSCF ab initio方法和3-21G基组,求得了HNO和HON的平衡几何构型及它们的重排反应的过渡态;并用数值方法求得了反应体系的力常数矩阵;从过渡态力常数矩阵的唯一负本征值相应的本征向量出发,求出了反应的内禀反应坐标(IRC)。经这个反应途径的振动分析和曲率计算表明:沿反应途径,N=O伸缩振动是绝热的,而H原子的伸缩振动则是一个动态自由度,IRC的曲率主要由这个正则坐标组成;沿反应途径IRC的曲率有2个尖锐的峰值,表明在这2个点附近,将会有动态学的效应发生。
In this paper, the equilibrium geometry of HNO and HON and the transition states of their rearrangement were obtained by using the MCSCF ab initio method with analytical gradient and the 3-21G basis set. The force constant matrix of the reaction system was obtained numerically. Starting from the eigenvectors corresponding to the only negative eigenvalues of the transition state force constant matrices, the intrinsic reaction coordinate (IRC) of the reaction is determined. The vibration analysis and curvature calculation of this reaction route show that: the N = O stretching vibration is adiabatic along the reaction path, while the stretching vibration of H atom is a dynamic degree of freedom. The curvature of IRC mainly consists of this regular coordinate. Along the reaction The curvature of the approach IRC has two sharp peaks, indicating that there will be a dynamic effect near these two points.