O^++H_2→OH^++H反应的动力学研究

Dynamics studies of O^+ + H_2→OH^+ + H reaction

采用含时量子波包方法结合二阶分裂算符传播子对初始态为(v=0, j=0)的O^++H_2→OH^++H反应体系在0.01—1.00 eV的碰撞能范围内进行了态分辨理论水平上的动力学计算.对反应概率、积分截面、微分截面以及固定初始态的热速率常数等动力学信息进行了计算并与文献报道的实验和理论结果进行了比较.结果表明本文的理论结果与实验结果十分符合.从微分截面的散射信息可知,在低碰撞能范围内,插入反应机制在反应中占据主导地位.随着碰撞能的增加,反应机制逐渐由插入机制变为抽取反应机制.

In the present work,the long-range interaction potential part of potential energy surface(PES)of OH2+system is revised and the new resulting PES apparently is more reasonable than the old one in the long-range part.Based on the new PES,the dynamics calculations of O++H2→OH++H reaction are carried out at a state-to-state level of theory by using time-dependent quantum wave packet method with second order split operator in a collision energy range from 0.01 to 1.0 eV.The dynamic properties such as reaction probability,ro-vibrational resolved statereaction probability,integral cross section,differential cross section,and state specific rate constant are calculated and compared with available theoretical and experimental results.The results of ro-vibrational resolved state reaction probability reflect some dynamic properties such as resonances which is attributed to the deep well located on the reaction path.The vibrational resolved state reaction probability indicates that the excitation efficiency of the OH+product is relatively low.The results of integral cross sections indicate that the present results are in better agreement with the experimental values than with previous theoretical calculations,especially in the low collision energy region.However,the state specific rate constant results underestimate the experimental values.The comparison betweenour calculations and the experimental results indicates that the contribution of the rotational excitation of H2 molecule should be included in the calculations.However,only the initial state v=0,j=0 is calculated in the present work.We suppose that the deviation of the present results from the experimental data is due to the fact that the rotational excitation of reactant isnot included in the present calculation.The differential cross section signals indicate that the complex-forming reaction mechanism isdominated in the case of low collision energy,but it transforms into abstract reaction mechanism as the collision energy further increases.