General internal coordinate gradient vectors and the vibrational kinetic energy operator of centrally-connected penta-atomic systems. Part I

Manson, Steven A.; Law, Mark M.

doi:10.1039/b603106d

Cited by 15 publications

(24 citation statements)

References 57 publications

(105 reference statements)

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“…Many exact forms of Hamiltonian have been derived in terms of curvilinear internal coordinates, such as valence coordinates and orthogonal coordinates [14,15], and used for large molecular systems [16,17]. The internal coordinates are geometrically defined and span a curvilinear configuration space.…”

Section: Generalized Internal Coordinatesmentioning

confidence: 99%

A simple method for derivation of the rovibrational Hamiltonian: application to orthogonal radau coordinate systems as special cases

Ebrahimi

Tafazzoli

Islampour

2010

JICS

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The molecular Hamiltonian of polyatomic molecules has been obtained. A general choice of internal coordinates depending on external parameters was considered. The rovibrational Hamiltonian for this set of coordinate system was derived in general terms as a function of the external parameters a and b. This procedure is also applicable to various kinds of internal coordinates in a straightforward way. The rovibrational Hamiltonian of triatomic molecules is considered as an application of this general formulation. In addition, orthogonal Radau coordinates are considered as cases of this new approach.

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Section: Generalized Internal Coordinatesmentioning

confidence: 99%

A simple method for derivation of the rovibrational Hamiltonian: application to orthogonal radau coordinate systems as special cases

Ebrahimi

Tafazzoli

Islampour

2010

JICS

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“…20,21 Although the rovibrational spectrum of CH 3 F has been well documented, its theoretical description is not reflective of the current state-of-the-art in variational calculations. Notable recent works include the PESs and energy level computations of Manson et al 22,23 , Nikitin, Rey, and Tyuterev 24 and Zhao et al 25,26 . Theoretical CH 3 F spectra are also available from the TheoReTS database 27 for a temperature range of 70-300 K but details on the calculations are unpublished except for the PES.…”

Section: Introductionmentioning

confidence: 99%

The rotation–vibration spectrum of methyl fluoride from first principles

Owens

Yachmenev

Küpper

et al. 2019

Phys. Chem. Chem. Phys.

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Accurate ab initio calculations on the rotation-vibration spectrum of methyl fluoride (CH3F) are reported. A new nine-dimensional potential energy surface (PES) and dipole moment surface (DMS) have been generated using high-level electronic structure methods. Notably, the PES was constructed from explicitly correlated coupled cluster calculations with extrapolation to the complete basis set limit and considered additional energy corrections to account for core-valence electron correlation, higher-order coupled cluster terms beyond perturbative triples, scalar relativistic effects, and the diagonal Born-Oppenheimer correction. The PES and DMS are evaluated through robust variational nuclear motion computations of pure rotational and vibrational energy levels, the equilibrium geometry of CH3F, vibrational transition moments, absolute line intensities of the ν6 band, and the rotation-vibration spectrum up to J = 40. The computed results show excellent agreement with a range of experimental sources, in particular the six fundamentals are reproduced with a root-mean-square error of 0.69 cm-1. This work represents the most accurate theoretical treatment of the rovibrational spectrum of CH3F to date.

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“…In most theoretical studies, large amplitude motions are presently used, which have an important effect on spectra. Many coordinates are commonly used to describe molecular configurations, such as internal coordinates and orthogonal coordinates [4][5][6]. In the last two decades, it has become feasible to obtain exact kinetic energy operators for molecules whose internal coordinates are employed for the calculation of large amplitude vibrations.…”

Section: Introductionmentioning

confidence: 99%

A new proof of the molecular Hamiltonian in Radau coordinates for triatomic molecules based on tensor form

Ebrahimi¹,

Tafazzoli²

2008

Molecular Physics

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A generalized coordinates molecular Hamiltonian for polyatomic molecules has been obtained. Using this Hamiltonian in Radau coordinates as the orthogonal coordinates, the molecular Hamiltonian is derived for triatomic molecules. An exact derivation is presented of the molecular Hamiltonian in different axis embedding such as bond embedding, bisector embedding, and the linear combination of Radau vector coordinates. In addition, the symmetrized Radau coordinates are considered as an example for this general formulation. This new approach is greatly simplified. Also presented are simple and explicit expressions without cross-terms in Radau coordinates as vibrational variables.

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General internal coordinate gradient vectors and the vibrational kinetic energy operator of centrally-connected penta-atomic systems. Part I

Cited by 15 publications

References 57 publications

A simple method for derivation of the rovibrational Hamiltonian: application to orthogonal radau coordinate systems as special cases

A simple method for derivation of the rovibrational Hamiltonian: application to orthogonal radau coordinate systems as special cases

The rotation–vibration spectrum of methyl fluoride from first principles

A new proof of the molecular Hamiltonian in Radau coordinates for triatomic molecules based on tensor form

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