AN IMPROVED POTENTIAL-ENERGY SURFACE OF AR-C2H2

The intermolecular interaction of the Ar-C2H2 system was investigated using the coupled-states approximation to analyze the scattering process at a collision, energy of 649.5 cm-1 (80.5 meV) and a close-coupling method to predict bound state energy levels. In both cases, the acetylene molecule is treated as a rigid rotor. A primary rainbow peak observed in the total differential scattering experiment provides useful information on the well depth while dimer rotational frequencies give accurate information on the shape around the minimum of the ground state potential. Four existing potentials for the system were tested against the total differential scattering cross section and rotational spectroscopic measurements. No one potential showed good agreement with both measurements. An improved potential energy surface was obtained by fitting simultaneously both scattering and spectroscopic data. © 1994 American Institute of Physics.