Dynamics of C&lt;sup&gt;+&lt;/sup&gt; + H&lt;sub&gt;2&lt;/sub&gt; reaction based on a new potential energy surface

Wen-Tao Li,Jie-Min Wang,Mei-Ling Yuan

doi:10.7498/aps.71.20212241

Abstract

The multi-reference interaction method is explicitly dependent on the electron-electron distance, and ACVQZ basis set is used in the ab initio calculation. The potential energy surface (PES) is fitted by using the permutation invariant polynomial neural network method based on 18222 ab initio points. In addition, the topographical features of the PES are compared with available theoretical and experimental data. The results indicate that the present PES is more accurate and can be applied to any type of dynamic study. In order to validate the PES, the dynamic study of the C+ + H2 → H + CH+ reaction is carried out by using the quasi-classical trajectory method in a collision energy range of 0.4–1.0 eV. The integral cross sections and differential cross sections are calculated and compared with previous theoretical studies. For the integral cross section, the present results are, in general, in good agreement with previous theoretical studies, both of which increase with collision energy increasing. The forward and backward symmetric differential cross sections indicate that the “complex-forming” mechanism plays a dominant role in the reaction.

Highlights

对于 CH+离子,平衡核间距 re,谐振频率ωe,离解能 De 与实验值的差距仅为 0.001 bohr,2.75 cm-1,3 meV。对于 H2 分子,平衡核间距 re 与实验结果一致, 谐振频率ωe 和离解能 De 与实验值的差距为 6.42 cm-1 和 5 meV。实验与理论的微小差距说明新构建的势能面很好的描述了当第三个原子远离另外两个原子时的势能曲线。
图 1 (a)键角在 136.68°时,化学键伸缩的等势线图。等势线的起点为-9.1 eV,等势线的间隔为 0.4 eV。(b)C+离子以 C2v 对称性接近 H2 分子中心的等势线图。等势线的起点为9.1 eV,等势线的间隔为 0.37 eV。 Figure 1 (a) Contour plot for chemical bond stretching, in which the angle is fixed at 136.68°
Contours starting at -9.1 eV and spaced by 0.4 eV. (b) Contour plot for the C+ ion approach to the midpoint of H2 molecule in the C2v symmetry

Summary

Introduction

对于 CH+离子,平衡核间距 re,谐振频率ωe,离解能 De 与实验值的差距仅为 0.001 bohr,2.75 cm-1,3 meV。对于 H2 分子,平衡核间距 re 与实验结果一致, 谐振频率ωe 和离解能 De 与实验值的差距为 6.42 cm-1 和 5 meV。实验与理论的微小差距说明新构建的势能面很好的描述了当第三个原子远离另外两个原子时的势能曲线。. 隐藏层,每个隐藏层包含 15 个神经元。此外,Levenberg-Marquardt 方法[39]用来其中,N 是总的能量点个数。 output是拟合值, 是从头算能量。对于本文的 CH2+体系,拟合 RMSE 仅为 1.27 meV。表 1 CH+和 H2 分子的光谱常数 Table 1 Spectroscopic constants of the CH+ and H2 molecules re (bohr) ωe (cm-1) ωexe (cm-1) βe (cm-1) CH+( 1Σ+)

Results

Conclusion