中文摘要：

采用CCSD（T）/6-311＋＋G（3df,2pd）//B3LYP/6-311＋G（2df,2p）双水平计算方法构建了HO_2＋HS反应体系的单、三重态反应势能面,并对该反应主通道的速率常数进行了研究。研究结果表明,标题反应经历了八条反应通道,其中三重态反应通道R1是标题反应主通道。此通道包含路径Path 1（R→^3IM1→^3TS1→P1（^3O_2＋H_2S））和Path 1a（R→^3IM1a→^3TS1a→P1（^3O_2＋H_2S））两条路径。利用经典过渡态理论（TST）与变分过渡态理论（CVT）并结合小曲率隧道效应模型（SCT）,分别计算了主路径Path 1和Path 1a在200-800 K温度范围内的速率常数k^TST、k^CVT和k^CVT/SCT,在此温度区间内路径Path 1和Path 1a具有负温度系数效应。速率常数计算结果显示,对主路径Path 1和Path 1a而言,变分效应在计算温度段内有一定影响,与此同时量子力学隧道效应在低温段有显著影响。路径Path 1和Path 1a的CVT/SCT速率常数的三参数表达式分别为k_1^CVT/SCT（200-800 K）=1.54×10^-5T^-2.70exp（1154/T）cm^3·molecule^-1·s^-1和k_（1a）^CVT/SCT（200-800 K）=5.82×10^-8T^-1.84exp（1388/T）cm^3·molecule^-1·s^-1。

英文摘要：

The mechanism for the biradical reaction of HS with HO_2 is investigated at the CCSD（T）/6-311＋＋G（3df,2pd）//B3LYP/6-311＋G（2df,2p） level on both the singlet and triplet potential energy surfaces, along with rate constant calculations of the major channel. The results show that there are eight reaction channels involved in the HS ＋ HO_2 reaction system. The major channel R1 of the title reaction occurs on the triplet potential energy surfaces, and includes two pathways： Path 1（R →^3IM1 →^3TS1 → P1（^3O_2＋ H_2S）） and Path 1a（R →^3IM1a →^3TS1a → P1（^3O_2＋ H_2S））. The rate constants k^TST, k^CVT, and k^CVT/SCT of Paths 1 and 1a for Channel R1 were evaluated using classical transition state theory（TST） and the canonical variational transition state theory（CVT）, in which the small-curvature tunneling correction was included. The calculated results show that k^TST, k^CVT, and k^CVT/SCT of these two pathways decrease with rising temperature within the temperature range of 200-800 K. The variational effect was not negligible in the entire process of Path 1 and Path 1a, at the same time, the tunneling effect was considerable at lower temperature. The fitted three-parameter expressions of k^CVT/SCT for Paths 1 and 1a are k_1^CVT/SCT（200-800 K） = 1.54 × 10^-5T^-2.70exp（1154/T） cm^3·molecule^-1·s^-1 and k_（1a）^CVT/SCT（200-800 K） = 5.82 × 10^-8T^-1.84exp（1388/T） cm^3·molecule^-1·s^-1, respectively.