The mechanism of the Au+2 catalyze CO and H2 O to form CO2 and H2 of the water-gas shift (WGS)cycle reaction has been considered on doublet and quartet potential energy surfaces in the gas phase.The UB3LYP density functional theory has been used in the reaction. All geometries are completed optimized.Transition states of the reaction are confirmed by the vibration frequency calculation and the intrinsic reaction coordinate analysis.Meanwhile,the possible of the potential energy surfaces (PESs)crossing has been discussed.The turnover frequency(fTO )is computed with the energetic span model by Kozuch,and the rate states are defined of the cycle reaction.The result shows that crossing points between the different PESs does not appear.The 2 TS34 and 2 IM1 are defined as rate-determining transition states(TDTS)and rate-determining intermediates(TDI),respectively.For the cycle reaction,δE and fTO are 237.6 kJ·mol-1 and 1.440×10-29 s-1 under the temperature of 298.15 K.%采用密度泛函理论中的 UB3LYP方法研究了气相中二聚体 Au+2在二重态与四重态势能面上催化 CO+H2 O→CO2+H2的水煤气变换(WGS)循环反应的机理.二、四重态势能面上各个驻点的几何构型被全参数优化,同时对过渡态进行了频率分析,并使用内禀反应坐标(IRC)方法对其进行了验证,讨论了势能面的交叉情况.运用 Kozuch 的能量跨度模型对循环反应中催化剂的转化频率(fTO )进行了计算,同时对整个反应的决速态进行了确定.结果表明,二、四重态势能面之间没有交叉点；循环反应中决速过渡态(TDTS)是2 TS34,决速中间体(TDI)是2 IM1；298.15 K下整个反应的δE=237.6 kJ·mol-1,fTO=1.440×10-29 s-1.
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