Abstract: 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.

Key words: Ab initio, Intermolecular potential, PES, CBS