Transition from molecular complex to quantum solvation in OCS(He)_N

Abstract

We present quantum calculations of the rotational energy levels and spectroscopic rotational constants of the linear OCS molecule in variable size clusters of 4He, using spectral evolution quantum Monte Carlo methods that allow excited states to be accessed without nodal constraints. 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 a value in excellent agreement with experimental measurements made on significantly larger clusters (N>1000). 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 non-zero permutation exchanges and a smaller extent of rigid coupling.

4 pages, 1 figure, submitted to Phys. Rev. Lett. on July 18,2002

References in corpus (2)

• The Rotational Structure of Molecules In the Quantum He4 and He3 Liquids
• Importance Sampling in Rigid Body Diffusion Monte Carlo

Cited by in corpus (12)

• Structure, rotational dynamics, and superfluidity of small OCS-doped He clusters
• Computational spectroscopy of helium-solvated molecules: effective inertia, from small He clusters toward the nano-droplet regime
• Quantum Rotation of HCN and DCN in Helium-4
• OCS in small para-hydrogen clusters: energetics and structure with N=1-8 complexed hydrogen molecules
• Rotational dynamics of CO solvated in small He clusters: a quantum Monte Carlo study
• Fingerprints of angulon instabilities in the spectra of matrix-isolated molecules
• Comparison of Rotational Energies and Rigidity of OCS-paraH_2 and OCS-4He complexes
• Three new infrared bands of the He-OCS complex
• Microscopic Computational Model of a Superfluid
• Quantum dynamics of molecules in 4He nano-droplets: Microscopic Superfluidity
• Structure and spectroscopy of doped helium clusters using quantum Monte Carlo techniques
• The He2 - OCS complex: comparison between theory and experiment