Ab   initio and scaled potential energy surfaces for Ar–C2H2: Comparison with scattering and spectroscopic experiments

New coupled-cluster ab initio potential energy surfaces (PES’s) were determined for the interaction of Ar with a rigid acetylene molecule. These PES’s were in addition modified by scaling the correlation energy. Based on both the original and scaled PES’s, close-coupled calculations of the total differential scattering cross section were carried out. Rovibrational energy levels of the Ar–C2H2 complex were computed variationally. In addition, we simulated the ir spectra corresponding to excitation of the upper diad of the ν3/ν2+ν4+ν5 excited molecular vibrational states. The comparison of all these quantities with experiment shows generally good agreement for the several scaled PES’s. In addition, the sensitivity of the PES to the experimental data are investigated by varying the scaling factor. The original and scaled PES’s are also compared with several phenomenological PES’s and a previously published ab initio PES [F.-M. Tao, S. Drucker, and W. Klemperer, J. Chem. Phys. 102, 7289 (1995)].