HF in clusters of molecular hydrogen. I. Size evolution of quantum solvation by parahydrogen molecules

Hao Jiang, Zlatko Bacic

Research output: Contribution to journalArticle

Abstract

We present a theoretical study of the quantum solvation of the HF molecule by a small number of parahydrogen molecules, having n=1-13 solvent particles. The minimum-energy cluster structures determined for n=1-12 have all of the H2 molecules in the first solvent shell. The first solvent shell closes at n=12 and its geometry is icosahedral, with the HF molecule at the center. The quantum-mechanical ground-state properties of the clusters are calculated exactly using the diffusion Monte Carlo method. The zero-point energy of (p- H2) n HF clusters is unusually large, amounting to 86% of the potential well depth for n>7. The radial probability distribution functions (PDFs) confirm that the first solvent shell is complete for n=12, and that the 13th p- H2 molecule begins to fill the second solvent shell. The p- H2 molecules execute large-amplitude motions and are highly mobile, making the solvent cage exceptionally fluxional. The anisotropy of the solvent, very pronounced for small clusters, decreases rapidly with increasing n, so that for n∼8-9 the solvent environment is practically isotropic. The analysis of the pair angular PDF reveals that for a given n, the parahydrogen solvent density around the HF is modulated in a pattern which clearly reflects the lowest-energy cluster configuration. The rigidity of the solvent clusters displays an interesting size dependence, increasing from n=6 to 9, becoming floppier for n=10, and increasing again up to n=12, as the solvent shell is filled. The rigidity of the solvent cage appears to reach its maximum for n=12, the point at which the first solvent shell is closed.

Original languageEnglish (US)
Article number244306
JournalJournal of Chemical Physics
Volume122
Issue number24
DOIs
StatePublished - 2005

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Solvation
solvation
Hydrogen
Molecules
hydrogen
molecules
probability distribution functions
rigidity
Rigidity
Probability distributions
Distribution functions
zero point energy
Ground state
Monte Carlo method
Anisotropy
Monte Carlo methods

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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HF in clusters of molecular hydrogen. I. Size evolution of quantum solvation by parahydrogen molecules. / Jiang, Hao; Bacic, Zlatko.

In: Journal of Chemical Physics, Vol. 122, No. 24, 244306, 2005.

Research output: Contribution to journalArticle

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