He-H_2(D_2,T_2)碰撞体系振转相互作用势及分波截面的理论计算

Theoretical calculation of the vib-rotational interaction potential and the partial wave cross sections for He-H_2 (D_2 ,T_2) system

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,选择由原子中心高斯函数和高斯键函数3s3p2d1f组成的大基组,计算了He-H2(D2,T2)碰撞体系的H2分子取不同键长时的相互作用势能面.运用Tang-Toennies势模型和非线性最小二乘法拟合构造了He与同位素分子H2(D2,T2)在质心坐标系下的振转相互作用势.通过密耦计算得到了入射原子能量分别为60,90和120meV时,各碰撞体系分波截面的信息.根据计算结果,进一步分析讨论了分波截面随量子数J变化的规律,并结合经典碰撞理论讨论了分波截面与碰撞参数bl的对应关系及散射特征.

The interaction potential surfaces of He-H2 （ D2,T2 ） have been 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 atomic centre Gaussian function and the 3s3p2d1f key function when the key-lengths of H2 was different. The vib-rotational interaction potentials of He-H2 （ D2,T2 ） system were fitted using the Tang-Toennies potential function and nonlinear least square method in a center of mass coordinate system. The partial wave cross sections at the energies of 60,90 and 120 meV have been calculated by using the quantum close-coupling method. On the basis of the above results,the change rules of the partial wave cross sections with change of quantum number have been obtained. Furthermore,corresponding connection and scattering characteristics of partial wave cross sections and scattering parameter were discussed in combination with classical collision theory.