Calculation of the intermolecular potential energy surfaces of HeH3+ by means of ab initio methods

The potential energy surface (PES) of a HeH3+ system for different orientations of monomers is calculated with the CCSD(T) method. The interaction energies obtained through aug-cc-pVDZ and aug-cc-pVTZ basis sets are extrapolated to a complete basis set limit using an extrapolated scheme. The study of the effects of different basis sets shows that the basis set used in this research is efficient in terms of accuracy and the time needed to perform calculations. To improve the quality of PES, fitting curves and the counterpoise correction method are used to determine the basis set superposition error for all the calculations. Finally, a three-dimensional plot of the intermolecular potential energy surface is drawn along with its contour plot of the potential intermolecular interaction. The second virial coefficient is also determined over a wide range of temperature for the He H-3(+) system.