Bound and unbound rovibrational states of the methane-argon dimer

Ferenc, Dávid; Mátyus, Edit

doi:10.1080/00268976.2018.1547430

Cited by 15 publications

(25 citation statements)

References 22 publications

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“…Any of the four hydrogen atoms of the methane can bind to the fluoride, which gives rise to the four equivalent wells and these wells are connected with 'surmountable' barriers. Thereby, the MS group of the complex is T d (M), for which the symmetry analysis of (the global minimum of) CH 4 ·Ar [30], can be adopted.…”

Section: Theoretical and Computational Detailsmentioning

confidence: 99%

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

Avila

Mátyus

2019

The Journal of Chemical Physics

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The complex of a methane molecule and a fluoride anion represents a 12-dimensional (12D) vibrational problem with multiple large-amplitude motions, which has challenged the quantum dynamics community for years. The present work reports the near 70 lowest-energy vibrational states, up to 730 cm −1 above the zero-point vibrational energy, obtained in a full-dimensional variational vibrational computation using the GENIUSH program and the Smolyak quadrature scheme. The vibrational energies and tunneling splittings are estimated to be converged better than 1 cm −1 and 0.05 cm −1 , respectively. The vibrational level structure confirms complementary aspects of the earlier full-and reduced-dimensionality computations of this six-atomic, four-well system: (1) the tunneling splittings, in the computed range, are smaller than 0.05 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 as a result (3) a full-dimensional treatment appears to be necessary. With further development of the quantum dynamics methodology and the potential energy surface, it will become possible to study highly-excited tunneling manifolds, with perhaps larger splittings indicated by reduced-dimensionality results, as well as predissociation phenomena. * Electronic address: Gustavo˙Avila@telefonica.net † Electronic address: matyuse@caesar.elte.hu

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Section: Theoretical and Computational Detailsmentioning

confidence: 99%

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

Avila

Mátyus

2019

The Journal of Chemical Physics

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“…There are several possibilities to describe the vibrational motion along the methane-argon distance. One can use L (α) n generalized Laguerre basis functions (with α = 2) [13,36] or a Morse tridiagonal basis set. The Laguerre basis set is a better choice for computing predissociative states, whereas the Morse tridiagonal basis set offers a more compact alternative for bound states.…”

Section: B Intermolecular Radial Representationmentioning

confidence: 99%

“…In the '3D( B 0 )' column, we report the bound vibrational energies obtained with an 'adjusted' 3D model. While using the r C-H 0 value for defining the 3D cut of the PES, we adjusted the C-H distance in the KEO to reproduce the B 0 effective rotational constant of this PES in 2D coupled-rotor computations [8,36]. This model reproduces the correct number of bound states and has a smaller, 0.32 cm −1 rms, than the 3D model with the rigorous geometrical constraints.…”

Section: Full-dimensional (12d) Vibrational States and Comparison mentioning

confidence: 99%

“…angular momentum quantum number of the methane fragment and the relative diatom in the [j, j] 00 dominant coupled-rotor (CR) function [36]; n R : vibrational excitation along R; Γ: irrep label of the T d (M) molecular symmetry group of the complex based on the CR assignment and irrep decomposition [36]. b ∆ k =ν(b = k) −ν(b = 3).…”

Section: Full-dimensional (12d) Vibrational States and Comparison mentioning

confidence: 99%

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Exact quantum dynamics background of dispersion interactions: case study for CH₄·Ar in full (12) dimensions

Avila

Papp

Czakó

et al. 2020

Phys. Chem. Chem. Phys.

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A full-dimensional ab initio potential energy surface of spectroscopic quality is developed for the van-der-Waals complex of a methane molecule and an argon atom. Variational vibrational states are computed on this surface including all twelve (12) vibrational degrees of freedom of the methaneargon complex using the GENIUSH computer program and the Smolyak sparse grid method.The full-dimensional computations make it possible to study fine details of the interaction and distortion effects and to make a direct assessment of the reduced-dimensionality models often used in the quantum dynamics study of weakly bound complexes. A 12-dimensional (12D) vibrational computation including only a single harmonic oscillator basis function (9D) to describe the methane fragment (for which we use the ground-state effective structure as the reference structure) has a 0.40 cm −1 root-mean-square error (rms) with respect to the converged 12D bound-state excitation energies, which is less than half of the rms of the 3D model set up with the r 0 methane structure.Allowing 10 basis functions for the methane fragment, the rms of the bound state vibrational energies is reduced to 0.07 cm −1 , which is much better than the 3D models. The full-dimensional potential energy surface correctly describes the dissociation of the system, which together with further development of the variational (ro)vibrational methodology opens the route for the study of the role of dispersion forces on the excited methane vibrations and the energy transfer from the intra-to the intermolecular vibrational modes. * Gustavo Avila@telefonica.net †

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“…Triatomic systems treated in this Special Issue include H 3 + [9] and Ca + -Ar 2 [10], for which accurate potential energy surfaces have been developed. We also learn how to understand certain characteristics of the motions of quantum systems from variationally computed wavefunctions [11] and about the nuclear dynamics of the CH 4 -Ar complex [12], formic acid [13], heavy protonated noble-gas species [14], the methanol cation under the influence of strong laser fields [15], and nitrosamine [16]. One of the goals of this Special Issue has been to address the treatment of nuclear motions of clusters.…”

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confidence: 99%

Special issue: atoms, molecules, and clusters in motion

Császár

Hochlaf

2019

Molecular Physics

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Bound and unbound rovibrational states of the methane-argon dimer

Cited by 15 publications

References 22 publications

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

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

Exact quantum dynamics background of dispersion interactions: case study for CH₄·Ar in full (12) dimensions

Special issue: atoms, molecules, and clusters in motion

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Bound and unbound rovibrational states of the methane-argon dimer

Cited by 15 publications

References 22 publications

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

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

Exact quantum dynamics background of dispersion interactions: case study for CH4·Ar in full (12) dimensions

Special issue: atoms, molecules, and clusters in motion

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Product

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Exact quantum dynamics background of dispersion interactions: case study for CH₄·Ar in full (12) dimensions