Ab Initio Intermolecular Potential Energy Surface of CO2-C2H2 Complex.

A new four-dimensional potential energy surface for CO2-C2H2 complex has been calculated by the ab initio methods at MP2/cc-pVXZ and MP2/aug-cc-pVXZ theory. For calculating the PES of the CO2-C2H2 complex, we have chosen to follow the supermolecule approach. The complete basis set limit of potential energy surface has been taken by extrapolation. Our MP2 results showed the most stable form of CO2-C2H2 complex is a parallel configuration. The complete basis set limit of ab initio potential energy surfaces have fitted to an analytic function and performance of fitting assessed. The electrostatic contribution to the PES has calculated and shows that it is anisotropic.