Ab initio anharmonic intermolecular potential of the C2H2–HCl hydrogen bonded complex

A grid calculation of the intermolecular potential of the hydrogen bonded C2H2–HCl complex has been performed at the CCSD(T)/cc-pVTZ level of theory. The effects of anharmonicity, of coupling between intramolecular and intermolecular motions, and of the basis set superposition error (BSSE) are independently considered. This calculation yields the center of mass separation of the complex, vibrationaly averaged and corrected of BSSE. It also provides the binding energy De and the anharmonic vibrational frequency shift of the νHCL band of the complex correlated with the HCl stretching mode. These properties are compared with experimental results and found to be in very good agreement.