Full-dimensional (12D) variational vibrational states of CH4·F-: Interplay of anharmonicity and tunneling

Gustavo Avila, Edit Matyus

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Abstract

The complex of a methane molecule and a fluoride anion represents a 12-dimensional (12D), four-well vibrational problem with multiple large-amplitude motions, which has challenged the quantum dynamics community for years. The present work reports vibrational band origins and tunneling splittings obtained in a full-dimensional variational vibrational computation using the GENIUSH program and the Smolyak quadrature scheme. The converged 12D vibrational band origins and tunneling splittings confirm complementary aspects of the earlier full- A nd reduced-dimensionality studies: (1) the tunneling splittings are smaller than 0.02 cm-1; (2) a single-well treatment is not sufficient (except perhaps the zero-point vibration) due to a significant anharmonicity over the wells; and thus, (3) a full-dimensional treatment appears to be necessary. The present computations extend to a higher energy range than earlier work, show that the tunneling splittings increase upon vibrational excitation of the complex, and indicate non-negligible "heavy-atom" tunneling.

Original languageEnglish
Article number154301
JournalJournal of Chemical Physics
Volume151
Issue number15
DOIs
Publication statusPublished - Oct 21 2019

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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