Localized helium excitations in 4He_N-benzene clusters

Abstract

We compute ground and excited state properties of small helium clusters 4He_N containing a single benzene impurity molecule. Ground-state structures and energies are obtained for N=1,2,3,14 from importance-sampled, rigid-body diffusion Monte Carlo (DMC). Excited state energies due to helium vibrational motion near the molecule surface are evaluated using the projection operator, imaginary time spectral evolution (POITSE) method. We find excitation energies of up to ~23 K above the ground state. These states all possess vibrational character of helium atoms in a highly anisotropic potential due to the aromatic molecule, and can be categorized in terms of localized and collective vibrational modes. These results appear to provide precursors for a transition from localized to collective helium excitations at molecular nanosubstrates of increasing size. We discuss the implications of these results for analysis of anomalous spectral features in recent spectroscopic studies of large aromatic molecules in helium clusters.

15 pages, 5 figures, submitted to Phys. Rev. B

References in corpus (5)

• Structural and dynamical properties of superfluid helium: a density functional approach
• Monolayer Solid Helium-4 Clusters on Graphite
• Many-body trial wave functions for atomic systems and ground states of small noble gas clusters
• Importance Sampling in Rigid Body Diffusion Monte Carlo
• Quadratic diffusion Monte Carlo and pure estimators for atoms

Cited by in corpus (5)

• 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
• UV spectra of benzene isotopomers and dimers in helium nanodroplets
• Structure and energetics of helium adsorption on nanosurfaces
• Accurate Helium-Benzene Potential: from CCSD(T) to Gaussian Process Regression