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中国物理学会期刊

\textD + \textSi\textD^ + \to \textD_2 + \textS\texti^ + 反应量子波包动力学研究

CSTR: 32037.14.aps.71.20221155

Quantum dynamics studies of the \rm D+SiD^+ \to D_2+Si^ + reaction

CSTR: 32037.14.aps.71.20221155
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  • 本文基于最新构建的\rmSiH_2^+(\tilde\rmX^3\rmA'')势能面, 运用切比雪夫波包方法, 对初始态为 \nu = 0, j = 0 \textD + \textSi\textD^ + 反应体系在 1.0 \times 10^ - 3 —1.0 eV的碰撞能量范围内进行动力学研究. 通过对角动量量子数 J \leqslant 110 的所有分波进行计算, 运用耦合态近似和考虑科里奥利耦合效应的精确量子力学两种方法, 得到该反应的反应概率、积分散射截面和速率常数. 文章详细分析了碰撞能量和科里奥利耦合效应对该反应的动力学性质的影响, 并与H+SiH+反应做了对比. 结果表明, 忽略科里奥利耦合效应会使D +SiD+反应积分散射截面和速率常数增大. 与H+SiH+反应动力学相比较, D +SiD+反应的积分反应截面的值较小且随着能量的衰减非常缓慢, 在低能区没有H+SiH+随能量增大而剧烈衰减的情况. 计算发现, 相同温度下, D +SiD+反应速率常数小于H +SiH+反应速率常数, 随着温度的升高, 二者的差距减小. 这表明, 同位素替代对反应的动力学性质有明显的影响.

     

    The quantum dynamics calculations are carried out for the title reaction D +SiD+→D2+Si+ to obtain the initial ( \nu = 0\text ,j = 0 )reaction probability, integral cross section (ICS) and rate constant on the potential energy surface (PES) of Gao, Meng and Song. A total of 110 partial waves are calculated by using the Chebyshev wave packet method with full Coriolis coupling (CC) and centrifugal sudden (CS) approximation in a collision energy range from 1.0 × 10–3 to 1.0 eV. The calculated probability decreases with the collision energy increasing except for J≤40. The calculation results indicate that the CS approximation will overestimate or underestimate the reaction probability . The ICS decreases with the collision energy increasing and shows an oscillatory structure due to the\rmSiH_2^+ well on the reaction path. The results show that the neglect of the Coriolis coupling leads to the overestimation of the cross section and the rate constant. Besides, the discrepancy between the integral cross sections from the CC and CS calculations decreases clearly with collision energy increasing. Comparison with the corresponding results of H+CH+ reaction indicates that isotope substitution reaction makes the cross section and the rate constant underestimated. The resulting integral reaction cross section displays less oscillatory structure, especially in the exact quantum calculation with the full Coriolis coupling effect taken into consideration. The kinetic isotope effect (\kappa_\rm H+SiH^+(T)/\kappa_\rm D+SiD^+(T))is found to decrease with temperature increasing. It can be seen that the reduced mass of reactant can exert a certain effect on dynamic behavior.

     

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