Rg—HX(Rg=He,Ne;X=F,Cl,Br)分子间势的精确量子化学从头计算研究 Ⅲ.基态He—HBr

High Level ab initio Study of Intermolecular Potential for the Rg-HX (Rg=He, Ne; X=F, Cl, Br) Complexes Ⅲ. He-HBr

在用非迭代的三重激发项来校正CCSD的CCSD(T)理论水平下 ,采用aug cc pVQZ基函数对He—HBr的分子间势进行了系统的研究 .结果表明 :He—HBr以线型结构存在 .在极限基的情况下 ,复合物两种线型极小点结构He—H—Br和He—Br—H势阱深分别为 2 8.792cm- 1 和 35 .70 7cm- 1 ,对应He原子到HBr分子质心的距离R分别为0 .40 7nm和 0 .34 3nm .讨论了不同的基函数和理论方法在研究此类弱束缚态复合物的分子间势时的可靠性及其对结果的影响 。

The potential energy surfaces of ground state of He-HBr complex have been calculated at several levels of theory, including the single and double excitation coupled-cluster method with noniterative perturbation treatment of triple excitation CCSD(T). Calculations have been performed using the augmented correlation-consistent polarized quadruple zeta basis set (aug-cc-pVQZ). Using the complete basis set (CBS), the global minimum with a well depth of approximately 28.792 cm -1 has been found for the linear He-H-Br geo^me^try (θ=0.0°) with the distance R between the He atom and the center of mass of the HBr molecule equal to 0.407 nm. In addition to the global minimum, there is a second minimum at R=0.343 nm and θ=180° (a well depth of 35.707 cm -1). Finally the effects of the basis sets and theoretical methods on the intermole^cul^ar potential are discussed and a simple analytic form employing 17 adjustable parameters for fitting to the calculated PES is given.