Simultaneous Determination of Force Constants and Dipole Moment Derivatives of Methane

Mourbat, A.; Aboumajd, A.; Loëte, M.

doi:10.1006/jmsp.1998.7575

Cited by 14 publications

(10 citation statements)

References 34 publications

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“…Examples of such an exercise can be found in Refs. [43,69]. For example, the parameter V 0(0,0A1) 0000A 1 −0001F 2 = 0.098677(88) D [47] is in good agreement with our value √ 3μ Table 1).…”

Section: Transition Momentssupporting

confidence: 83%

Vibrational transition moments of CH4 from first principles

Yurchenko

Tennyson

Barber

et al. 2013

Journal of Molecular Spectroscopy

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A new nine-dimensional (9D), ab initio electric dipole moment surface (DMS) of methane in its ground electronic state is presented. The DMS is computed using an explicitly correlated coupled cluster CCSD(T)-F12 method in conjunction with an F12-optimized correlation consistent basis set of the TZ-family. A symmetrized molecular bond representation is used to parameterise the 9D DMS in terms of sixth-order polynomials. Vibrational transition moments as well as band intensities for a large number of IR-active vibrational bands of 12 CH 4 are computed by vibrationally averaging the ab initio dipole moment components. The vibrational wavefunctions required for these averages are computed variationally using the program TROVE and a new 'spectroscopic' 12 CH 4 potential energy surface. The new DMS will be used to produce a hot line list for 12 CH 4 .

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Section: Transition Momentssupporting

confidence: 83%

Vibrational transition moments of CH4 from first principles

Yurchenko

Tennyson

Barber

et al. 2013

Journal of Molecular Spectroscopy

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“…The sign convention for the normal coordinates is that of Gray and Robiette [15], so the signs of the derivatives including q 2a and q 2b of Loete [46] have been changed accordingly, (see also Tab. 4 of Mourbat et al [47]). Table 2 Comparison with experiment [13] of calculated transition wave numbers and intensities for the R-branch of methane vibrational ground state.…”

Section: Resultsmentioning

confidence: 90%

“…In the same vein, a simultaneous determination of force constants and dipole moment first and (some) second derivatives of methane was performed by Mourbat et al [47]. First order derivatives were calculated ab initio by Hollenstein et al at the second order Moller-Plesset, double zeta plus polarization, MP2/DZP, level [48].…”

Section: Introductionmentioning

confidence: 99%

An improved third order dipole moment surface for methane

Cassam-Chenaı̈

Liévin

2013

Journal of Molecular Spectroscopy

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In a previous article a dipole moment surface (DMS) of full-electron, multi-reference configuration interaction (MRCI) quality was obtained and used to calculate the rotational spectrum of methane vibrational ground state, by means of a combination of the mean field configuration interaction method (VMFCI) with a generalized perturbation theory. The theoretical line intensities were matching the experimental ones obtained at the SOLEIL synchrotron well within experimental uncertainties.However, not all third order terms were included in this DMS. In the present work, additional DMS points have been calculated and fitted using a complete third order expansion. The new results give R-branch intensities systematically smaller by about 1 percent compared to those previously obtained by using the same ab initio method, so still within experimental errors. The relevance of this DMS to calculate intensities for excited vibrational states, in particular for the dyad, is addressed.

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“…Mourbat, Aboumajd, and Loëte determined the linear and quadratic dipole moment derivatives of CH 4 in terms of the symmetric internal coordinates by use of the experimental spectroscopic parameters. 26 This low-order DMS is not expected to give a good description for high overtone intensities of CH 4 . We will compute ab initio 4-D stretching DMS of CH 4 and SnH 4 in this work.…”

Section: Introductionmentioning

confidence: 94%

“…were used to calculate the DMS expansion coefficients up to third order by a finite-difference method, and the steps were set to 0.05 Å.The DMS expansion coefficients in this work are related to the dipole moment derivatives in Ref 26. as follows: C 1000 F 2z ϭM 3 , and C 2000 F 2z ϭ(M 33 ϩM 13 )/2, where M 13 was constrained to zero in the reference.…”

mentioning

confidence: 99%

Study of the stretching vibrational band intensities of XH4 molecules employing four-dimensional ab initio (X=C and Sn) and effective (X=C and Si) dipole moment surfaces

Liu

Lin

et al. 2002

The Journal of Chemical Physics

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An ab initio study of the betaine anion-dipole-bound anionic state of a model zwitterion system Stretching vibrational band intensities of XH 4 molecules were investigated employing four-dimensional ab initio (XvC and Sn͒ and effective (XvC and Si͒ dipole moment surfaces ͑DMS͒ in combination with the local mode potential energy surfaces. The ab initio DMS of CH 4 and SnH 4 calculated at the coupled cluster CCSD͑T͒ level of theory reproduced most of the observed intensities within a factor of 1.5. The effective DMS of CH 4 and SiH 4 were obtained by adjusting some selected high-order terms in the ab initio DMS to fit the observed intensities. They were applied to the corresponding deuterated isotopomers yielding better results than the ab initio DMS. The intensities of the combination bands are mainly due to the interbond cross terms in the DMS for SiH 4 , GeH 4 , and SnH 4 , while for CH 4 , both diagonal and cross terms are important. The relatively strong combination band that has comparable intensity with the pure overtone was predicted at the fourth local mode manifold for SnH 4 .

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Simultaneous Determination of Force Constants and Dipole Moment Derivatives of Methane

Cited by 14 publications

References 34 publications

Vibrational transition moments of CH4 from first principles

Vibrational transition moments of CH4 from first principles

An improved third order dipole moment surface for methane

Study of the stretching vibrational band intensities of XH4 molecules employing four-dimensional ab initio (X=C and Sn) and effective (X=C and Si) dipole moment surfaces

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