Transition from molecular complex to quantum solvation in 4HeNOCS -: art. no. 073401

We present fully quantum calculations of the rotational energy levels and spectroscopic rotational constants of the linear OCS molecule in variable size clusters of He-4. The rotational constants of OCS are found to decrease monotonically from the gas phase value as the number of helium atoms increases to N=6, after which the average constant increases to saturation at the large droplet value by N=20. The minimum is shown to indicate a transition from a molecular complex to a quantum solvated molecule, with the former characterized by floppy but near rigid behavior, while the latter is characterized by nonzero permutation exchanges and a smaller extent of rigid coupling.