The intermolecular potential energy surface of Ne···NCCN van der Waals complex was evaluated in the framework of the counterpoise-corrected supermolecular approach using CCSD(T) level and aug-cc-pVDZ basis set extended with a set of midbond (3s3p2d1f1g) functions. The effect of the place of midbond function on the accuracy of the calculated potential energy surface was examined and the optimised position for placing midbond function was determined. The calculated potential energy surface was fitted by an analytical function. The analytical function of intermolecular potential energy surface of Ne···NCCN demonstrated a global minimum energy of −12.024 meV related to the T-shape geometry at the distance between Ne and the centre of mass of NCCN of 3.28 A° . Finally, the interaction second virial coefficients (B12) of Ne and NCCN were calculated and used to calculate the second virial coefficients for the mixture of neon and cyanogen gases at different mole fractions of Ne gas.
