He-HI复合物势能面及微分散射截面的理论研究

采用超分子单双迭代(包括非迭代三重激发)耦合簇理论CCSD(T)方法和由键函数3s3p2d1f组成的大基组, 计算得到了基态He-HI复合物相互作用的全程势能面. 该势能面上存在2个势阱, 分别对应于线性He-I-H和He-H-I构型, 势阱深度分别为4.473和2.996meV, He原子到HI分子质心的距离R分别为0.363和0.442nm. 使用Barker, Fisher和Watts提出的BFW势函数拟合计算得到的相互作用能数据, 获得了He原子与HI分子相互作用势的解析表达式. 在 关键词： He-HI复合物 势能面 微分散射截面

Theoretical study of the potential energy surface and differential scattering cross sections of He-HI complex

The intermolecular potential energy surface for He-HI complex has been first calculated by employing supermolecule method and the single and double excitation coupled-cluster with a noniterative perturbation treatment of triple excitation CCSD(T) approach using a large basis set containing the bond function set 3s3p2d1f. The potential energy surface has two potential wells. The global minimum with a well depth of 4.473 meV has been found for the linear He-I-H configuration with R，the distance of the He atom and the center of mass of the HI molecule, of 0.363nm. In addition to the global minimum, there is a second minimum corresponding to the linear He-H-I configuration with a well depth of 2.996 meV and R of 0.442nm. Then the analytic expression of the interaction potential for the He-HI complex of the ground state has been obtained by utilizing the Barker potential-type analytic function to fit the calculated intermolecular energy data. On the basis of the above results, the differential scattering cross sections (DCS) at the energy of 100meV for collision between He atom and HI molecule have been calculated using the quantum close-coupling method. Finally, the validity of the potential energy surface of the He-HI system has been verified by comparing it with the CCSD(T) potential energy surface of the He-HX(X=F, Cl, Br) systems and by comparing their DCS at the same collision energy.