Rg-HX分子间势的精确从头计算研究

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 HF的分子间势进行了系统的研究.结果表明：He HF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 F和He F H势阱深分别为46.614 cm－1和25.026 cm－1,对应He原子到HF分子质心的距离Rm分别为0.3149 nm和0.3012 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，并研究了HF分子中H－F键长的改变对势能的影响,同时也给出了势函数的解析形式.

High Level ab Initio Study of Intermolecular Potential for the Rg-HX Complexs

The potential energy surfaces of the ground state of the He HF 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 46.614 cm－1 has been found for the linear He H F geometry (θ=0°) with the distance Rm between the He atom and the center of mass of the HF molecule equal to 0.3149 nm. In addition to the global minimum, there is a second minimum at R=0.3012 nm and θ=180° (a well depth of 25.026 cm－1). The effects of the basis sets, H－F bond length and theoretical methods on the intermolecular potential were discussed and a simple analytic form employing 17 adjustable parameters for fitting to the calculated PES was given.