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.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28.792 cm~(-1)和35.707 cm~(-1)，对应He原子到HBr分子质心的距离 R分别为0.407 nm和0.343 nm。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，同时也给出了热函数的解析形 式。

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

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 geometry (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 intermolecular potential are discussed and a simple analytic form employing 17 adjustable parameters for fitting to the calculated PES is given.