Uncertainty of the potential curve minimum for diatomic molecules extrapolated from Dunham type coefficients

Ilieva, Teodora; Iliev, I.; Pashov, A.

doi:10.1016/j.jms.2016.09.009

Cited by 7 publications

(3 citation statements)

References 4 publications

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“…The IHH potential energy model provides a quantitative description of the energy‐distance relationship on diatomic molecules, and is given by

U_{IHH} (r) = D_{e} [{((), 1 goodbreak- e^{- italicqx})}^{2} + σ_{1} x^{3} e^{- 2 x} (1 + σ_{2} x)],

where

D_{e}

represents the dissociation energy,

σ_{1}

and

σ_{2}

are two infinite dimensional constants which can be expressed as

σ_{1} = 1 + a_{1} \sqrt{\frac{D_{e}}{a_{0}}} = c_{1},

σ_{2} = - \frac{1}{2} [(\frac{a_{0} a_{2}}{D_{e}} - b^{3} \frac{3 λ^{2}}{2}) / b^{5} + \frac{1}{4} - 2 σ_{1}],

where

a_{0}, a_{1}, a_{2}

are the Dunham coefficients [21, 22] which can be denoted as

a_{0} = \frac{ω_{e}^{2}}{4 B_{e}},

a_{1} = - 1 - <...

…”

Section: Theoretical Methodsmentioning

confidence: 99%

Study on macroscopic thermodynamic properties of ClO molecule based on the improved Hulburt–Hirschfelder potential energy function

Fan

Wen

Jian

et al. 2022

Int J of Quantum Chemistry

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The improved Hulburt-Hirschfelder potential energy function is used as a proposal to emulate the behavior of intramolecular motion of a gas composed of diatomic molecules. In this work, the rovibrational energies of ClO molecule in the ground electronic state are obtained by solving the one-dimensional Schrödinger equation with the improved Hulburt-Hirschfelder potential energy curve. And then, the molar heat capacities, molar entropies, molar enthalpies and reduced Gibbs free energies of ClO macroscopic gas are calculated by the quantum statistical ensemble theory. The results are compared with those calculated by using RKR potential energy curve from experiment and Morse potential energy function. It is found that the macroscopic thermodynamic properties of ClO calculated by the improved Hulburt-Hirschfelder potential energy function are closer to the experimental values, which provides a new way to calculate the macroscopic thermodynamic quantities of diatomic gas based on molecular microscopic information.

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“…The IHH potential energy model provides a quantitative description of the energy‐distance relationship on diatomic molecules, and is given by

U_{IHH} (r) = D_{e} [{((), 1 goodbreak- e^{- italicqx})}^{2} + σ_{1} x^{3} e^{- 2 x} (1 + σ_{2} x)],

where

D_{e}

represents the dissociation energy,

σ_{1}

and

σ_{2}

are two infinite dimensional constants which can be expressed as

σ_{1} = 1 + a_{1} \sqrt{\frac{D_{e}}{a_{0}}} = c_{1},

σ_{2} = - \frac{1}{2} [(\frac{a_{0} a_{2}}{D_{e}} - b^{3} \frac{3 λ^{2}}{2}) / b^{5} + \frac{1}{4} - 2 σ_{1}],

where

a_{0}, a_{1}, a_{2}

are the Dunham coefficients [21, 22] which can be denoted as

a_{0} = \frac{ω_{e}^{2}}{4 B_{e}},

a_{1} = - 1 - <...

…”

Section: Theoretical Methodsmentioning

confidence: 99%

Study on macroscopic thermodynamic properties of ClO molecule based on the improved Hulburt–Hirschfelder potential energy function

Fan

Wen

Jian

et al. 2022

Int J of Quantum Chemistry

View full text Add to dashboard Cite

show abstract

“…The high-resolution grid is from 0.9 to 6.0 Å in steps of 0.005 Å (1021 points). Inexpensive guiding potentials are CASSCF(8,8)/cc-pVTZ and icMRCI (8,8)+Q/aug-cc-pwCVTZ using three-state-averaged orbitals. The X state is identified as the lower of the  = 0 states in the CASSCF, and as the icMRCI state dominated by that CASSCF reference.…”

Section: Computational Detailsmentioning

confidence: 99%

“…It should be noted that model dependence is also problematic in the reduction of data from experimental spectroscopy. Different models produce different values of meaningful parameters, [7,8] and analytical functions may fail to reproduce experimental data, [9] despite their great proliferation known as "potentiology." [10,11] Polyatomic potential-energy functions have a separate literature for smoothing functions, as a result of their greater dimensionality.…”

Section: Introductionmentioning

confidence: 99%

Physics-Guided Curve Fitting for ab Initio Diatomic Spectroscopy

Irikura

2022

Preprint

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When using ab initio calculations to predict the spectra of diatomic molecules, discrete ab initio data must be converted to continuous form. As in other applications of interpolation throughout science and engineering, high-resolution (i.e., fine-mesh) data are desirable so that the method of interpolation does not affect the final results. However, high-resolution data are seldom available, because of their high cost. Current practice to is use splines, polynomials, or Morse-like fitting functions for interpolation and even for extrapolation. The choice is arbitrary and affects the spectroscopic results more than is generally recognized. Here we suggest an alternative procedure, in which the physics of the problem is leveraged to provide more robust results. A high-resolution data set, from a less costly ab initio model of the system of interest, is used as a guiding function. The residuals must still be fitted using splines or polynomials, but the smaller magnitude and weaker structure of the residuals leads to improved stability and accuracy of the spectroscopic results. When two or more guiding potentials are available, they can be used to guide the selection of geometries to be computed at high level, thus improving computational efficiency.

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Potentiology and spectroscopy in honor of Robert Le Roy: A preface to the special issue

Gordon

Roy

2016

Journal of Molecular Spectroscopy

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Uncertainty of the potential curve minimum for diatomic molecules extrapolated from Dunham type coefficients

Cited by 7 publications

References 4 publications

Study on macroscopic thermodynamic properties of ClO molecule based on the improved Hulburt–Hirschfelder potential energy function

Study on macroscopic thermodynamic properties of ClO molecule based on the improved Hulburt–Hirschfelder potential energy function

Physics-Guided Curve Fitting for ab Initio Diatomic Spectroscopy

Potentiology and spectroscopy in honor of Robert Le Roy: A preface to the special issue

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