Coping with the anisotropy in the analytical representation of potential energy surfaces of van der Waals complexes

Ab initio calculations of potential energy surface (PES) of van der Walls complexes initially reproduce the PES in the form of tables of numbers and these numbers have to be interpolated or extrapolated for desired applications [1]. In the case of anisotropic interactions, the major difficulty arises when one attempts to obtain an analytical representation for the PES data points. Computational cost, Numerical accuracy and Physical reliability are the most important factors that influence the performance and success of this procedure. Recently an ab initio analytical PES was reported for F2 dimer [2]. In this work via an ab initio investigation of Cl2 dimer performance of different fitting strategies are examined and in comparison with similar results for F2 dimer the influence of anisotropy of PES on the ability of these approaches is investigated.