POTENTIAL-ENERGY SURFACE AND SPECTROSCOPY OF CLUSTERS OF RARE-GAS ATOMS WITH CYCLOPROPANE

Analytical empirical potential energy surfaces describing the van der Waals interaction between rare-gas atoms and cyclopropane are presente d. The functional form is based on pairwise Lennard-Jones-type potenti als which have been widely used to describe rare-gas-benzene complexes , also studied in this work in order to check our theoretical method a nd for comparison. The parameters have been chosen in order to accurat ely fit the high resolution microwave spectra recently reported by Xu and Jager [J. Chem. Phys. 106, 7968 (1997)]. The observed splitting in the microwave spectra of Ne-cyclopropane, associated with rotational tunneling, is well reproduced. Moreover, such tunneling is also import ant for complexes of Ar and Kr in excited van der Waals states. These phenomena involve a high delocalization of the wave functions and, the refore, intermolecular spectroscopy techniques would provide a good ch eck of the potential energy surface over a broad region of the configu ration space. (C) 1998 American Institute of Physics. [S0021-9606(98)0 0345-6].