Disentangling the IR spectra of 2,3,3,3-tetrafluoropropene using an ab initio description of vibrational polyads by means of canonical Van Vleck perturbation theory

Charmet, Andrea Pietropolli; Bizzocchi, L.; Giuliano, B. M.; Caselli, P.; Craig, Norman C.; Krasnoshchekov, S. V.

doi:10.1016/j.jqsrt.2019.106656

Cited by 6 publications

(6 citation statements)

References 121 publications

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“…The CVPT2/VCI(4) calculations in the numerical–analytic form were performed using the ANCO program 61,127 using essentially the same techniques as in our previous studies. 128–130 The obtained values of fundamental frequencies demonstrated sufficiently good agreement with the observed vibration–rotation band centers of about 0.1% (see Table 1). The residual errors of the calculation are within non-accounted typical fine quantum-mechanical electronic effects.…”

Section: Methods Of Calculationsupporting

confidence: 78%

Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H₂¹⁶O isotopologues

Chang

Dobrolyubov

Krasnoshchekov

2022

Phys. Chem. Chem. Phys.

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Section: Methods Of Calculationsupporting

confidence: 78%

Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H₂¹⁶O isotopologues

Chang

Dobrolyubov

Krasnoshchekov

2022

Phys. Chem. Chem. Phys.

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“…предыдущих исследованиях [62][63][64][65][66][67][68][69]. Для графического моделирования итоговых спектров для пика с энергией перехода E j и ИК интенсивностью I (IR) j…”

Section: методика расчетаunclassified

“…4), его эксперимен-тальное изучение затруднено наличием колебательновращательного кориолисова резонанса ν 3 /ν 8 , который подробно изучался в работах [27,29,35,38,39]. Согласно нашему расчету, в основной молекуле 12 C, 35 Наш опыт показывает [68], что трехквантовые переходы зачастую имеют невозмущенную интенсивность, достаточную для экспериментального наблюдения. Действительно, для основной молекулы, например, обнаруженное экспериментально при анализе спектра высокого разрешения состояние ν 4 + 2ν 9 (1143.6684 cm −1 ) [39] имеет предсказанную интенсивность 0.05 km/mol и частоту 1136.7 cm −1 при отсутствии заимствования интенсивности от ближайших " светлых" полос.…”

Section: колебательные резонансы и полиадное квантовое числоunclassified

Неэмпирический анализ изотопических сдвигов и резонансных эффектов в инфракрасном спектре высокого разрешения фреона-22 (CHF-=SUB=-2-=/SUB=-Cl), обогащенного -=SUP=-13-=/SUP=-C

Краснощеков¹,

Гайнуллин²,

Лаптев³

et al. 2022

Оптика И Спектроскопия

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The IR transmittance spectrum of an isotopic mixture of chlorodifluoromethane (CHF2Cl, Freon-22) with a 33% fraction of 13C and a natural ratio of chlorine isotopes was measured in the frequency range 1400-740 cm–1 with a resolution of 0.001 cm–1 at a temperature of 20C. An ab initio calculation of the structure and sextic potential energy surface and surfaces of the components of the dipole moment has been carried out by the the electronic quantum-mechanical method of Möller-Plesset, MP2/cc-pVTZ. Then the potential was optimized by replacing the harmonic frequencies with the frequencies calculated by the electronic method of coupled clusters, CCSD(T)/aug-cc-pVQZ. The fundamental and combination frequencies were calculated using the operator perturbation theory of Van Vleck (CVPTn) of the second and fourth order (n=2,4). Resonance effects were modeled using an additional variational calculation in the basis up to fourfold VCI excitation (4). The average prediction error for the fundamental frequencies of the 12C isotopologues was ~1.5 cm–1. The achieved accuracy made it possible to reliably predict the isotopic frequency shifts of the 13C isotopologues. It is shown that the strong Fermi resonance ν4/2ν6 dominates in the 12C isotopologues and is practically absent in 13C. The literature assumption [Spectrochim. Acta A, 44: 553] about the splitting of ν1 (CH) due to the resonance ν1/ν2+ν7+ν9 is confirmed. The coefficients of the polyadic quantum number are determined. The analysis made it possible to carry out a preliminary identification of the centers of the vibrational-rotational bands of isotopologues 13CHF235Cl и 13CHF237Cl in the spectrum of the mixture in preparation for individual analyzes of the vibrational-rotational structures of individual vibrational transitions.

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“…Several works used alternative methods for the nuclear motion calculations for medium and large molecules using vibrational configuration-interaction approach or the perturbation theory (refs − and references herein). However, in most cases, the rotation states were computed for low J only and the contribution of hot bands have been neglected.…”

Section: Introductionmentioning

confidence: 99%

First Full-Dimensional Potential Energy and Dipole Moment Surfaces of SF₆

et al. 2020

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A 15-dimensional analytical form for the potential energy and dipole moment surfaces of the SF6 molecule in the ground electronic state is obtained using ab initio methods. In order to calculate the equilibrium S-F distance, we applied coupled cluster CCSD(T) method and several versions of the correlation consistent basis sets -from valence triple-zeta (VTZ) and augmented valence triple-zeta (AVTZ) to core-valence quadruple-zeta (CVQZ) with Douglas-Kroll (DK) relativistic corrections that provided good agreement with empirical equilibrium value. Ab initio electronic energies on 15D grids of nuclear geometries are computed using CCSD(T) method with VTZ and CVQZ-DK basis sets. The analytical representation of the potential energy surface is determined through an expansion in symmetry adapted products of non-linear coordinates up to the 5-th order. The influence of additional redundant coordinates on the quality of the fit was investigated. Parameters of full dimensional dipole moment surfaces are determined up to the 4th order expansion in normal mode coordinates. For validation of ab initio results, the fundamental vibration frequencies and absorption cross-sections of the principal sulfur hexafluoride isotopolgue are calculated giving good agreement with cold (180 K) and room temperature ( 296 K) experimental spectra. Absorption cross-sections calculated from our preliminary line list agree much better with these observations than the simulations using SF6 line-by-line lists constructed from effective models included in currently available spectroscopic databases.

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Disentangling the IR spectra of 2,3,3,3-tetrafluoropropene using an ab initio description of vibrational polyads by means of canonical Van Vleck perturbation theory

Cited by 6 publications

References 121 publications

Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H₂¹⁶O isotopologues

Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H₂¹⁶O isotopologues

Неэмпирический анализ изотопических сдвигов и резонансных эффектов в инфракрасном спектре высокого разрешения фреона-22 (CHF-=SUB=-2-=/SUB=-Cl), обогащенного -=SUP=-13-=/SUP=-C

First Full-Dimensional Potential Energy and Dipole Moment Surfaces of SF₆

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Disentangling the IR spectra of 2,3,3,3-tetrafluoropropene using an ab initio description of vibrational polyads by means of canonical Van Vleck perturbation theory

Cited by 6 publications

References 121 publications

Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H216O isotopologues

Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H216O isotopologues

Неэмпирический анализ изотопических сдвигов и резонансных эффектов в инфракрасном спектре высокого разрешения фреона-22 (CHF-=SUB=-2-=/SUB=-Cl), обогащенного -=SUP=-13-=/SUP=-C

First Full-Dimensional Potential Energy and Dipole Moment Surfaces of SF6

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Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H₂¹⁶O isotopologues

Fundamental studies of vibrational resonance phenomena by multivalued resummation of the divergent Rayleigh–Schrödinger perturbation theory series: deciphering polyad structures of three H₂¹⁶O isotopologues

First Full-Dimensional Potential Energy and Dipole Moment Surfaces of SF₆