砷化氢与氢原子反应速率常数的从头算研究

Ab initio study on the rate constants for the reaction of H_3As with H

用从头算法和变分过渡态理论研究氢提取反应:AsH3+H→AsH2+H2.在UQCISD/6-311+G(d,p)水平上优化了反应物、产物以及过渡态的结构参数,在相同水平上计算了反应物、产物及过渡态的谐振频率.用UQCISD(T)/6-311++G(2df,2pd)方法重新精确计算了反应物、产物和过渡态及反应路径上选择点的单点能,得到正反应势垒为7.3kJ/mol.在内禀反应坐标(IRC)的势能剖面基础上,用改进的变分过渡态理论计算了在250～1500K温度范围内反应的速率常数.

The hydrogen abstraction reaction of AsH3 with hydrogen atom has been studied using the direct dynamics. The geometries and frequencies of the reactants, products and TS as well as the selected points along the MEP at the UQCISD/6-311+G(d, p) level of theory were calculated. The energies of the reactants, TS, products and the selected points along the MEP were further improved at the UQCISD(T)/6-311++G(2df,2pd)// UQCISD/6-311+G(d, p) level of theory. The barrier height obtained for the forward reaction was 7.3 kJ/mol. The reaction rate constants calculated by the ICVT/SCT theory were good agreement with the experimental values.