Collisional rates based on the first potential energy surface of the NeH+ −He system

Bop, Cheikh T; Hammami, K.; Faye, Ndeye Arame Boye

doi:10.1093/mnras/stx1369

Cited by 15 publications

(14 citation statements)

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“…All these configurations were treated with the explicitly correlated coupled cluster method with single, double and non-iterative triple excitation (CCSD(T)-F12) (Knizia et al 2009) in conjunction with the augmented-correlation consistent-polarized valence triple zeta Gaussian basis set (aug-cc-pVTZ) (Dunning Jr 1989). For further details on the methodology followed, see Bop et al (2017). Such a level of theory (CCSD(T)-F12/au-cc-pVTZ) was used as implemented in the MOLPRO molecular package (Werner et al 2010).…”

Section: Potential Energy Surfacementioning

confidence: 99%

“…Such an approximation will significantly reduce the computational efforts. In fact, charged species strongly interact with He (Bop et al 2016(Bop et al , 2017(Bop et al , 2018 and then much more with H 2 leading to very deep potential wells. Such well depths supplemented by the low rotational constant of NS + (∼ 0.83 (Cernicharo et al 2018)) would make the dynamic calculations computationally expensive.…”

Section: Introductionmentioning

confidence: 99%

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Hyperfine excitation of NS+ due to para-H2(j = 0) impact

Bop

2019

Monthly Notices of the Royal Astronomical Society

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Sulphur bearing nitrogenous compounds have been observed in space over this last decade. Modelling their abundances has been done using rate coefficients of isoelectronic molecules. In order to satisfy the astrophysical precision required, we report the actual rate coefficients of NS+ induced by collision with the most abundant interstellar species (para-H2). Considering the 23 low-lying rotational levels of NS+, we were able to compute the (hyperfine) rate coefficients up to 100 K. These latter were carried out by averaging cross-sections over the Maxwell–Boltzmann velocity distribution. The state-to-state inelastic cross-sections were determined in the quantum mechanical close coupling approach for total energies ranging up to 1400 cm−1. These dynamic data result from a four dimensional potential energy surface (4D-PES) which was spherically averaged over the H2 orientations. The 4D-PES was calculated using the explicitly correlated coupled cluster method with simple, double, and non-iterative triple excitation (CCSD(T)–F12) connected to the augmented–correlation consistent–polarized valence triple zeta Gaussian basis set (aug–cc–pVTZ). The so-averaged PES presents a very deep well of 596.72 cm−1 at R = 5.94 a0 and θ1 = 123.20°. Discussions on the propensity rules for the (hyperfine) rate coefficients were made and they are in favour of (Δj = ΔF) Δj = 1 transitions. The results presented here may be crucially needed in order to accurately model the NS+ abundance in space. In addition, we expect that this paper will encourage investigations on the sulphur bearing nitrogenous compounds.

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Section: Potential Energy Surfacementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hyperfine excitation of NS+ due to para-H2(j = 0) impact

Bop

2019

Monthly Notices of the Royal Astronomical Society

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“…When going to the heteronuclear (Ng-H-Ng’) + , the situation changes even appreciably. The numerous calculations already available [ 33 , 34 , 43 , 55 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ] unravel, in fact, structurally asymmetric species, the (formal) H + being closer and more tightly bound to the atom having the higher proton affinity (PA). The difference between the PA of Ng and Ng’ may actually arrive up to ca.…”

Section: Introductionmentioning

confidence: 99%

On the Proton-Bound Noble Gas Dimers (Ng-H-Ng)+ and (Ng-H-Ng’)+ (Ng, Ng’ = He-Xe): Relationships between Structure, Stability, and Bonding Character

2021

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The structure, stability, and bonding character of fifteen (Ng-H-Ng)+ and (Ng-H-Ng')+ (Ng, Ng' = He-Xe) compounds were explored by theoretical calculations performed at the coupled cluster level of theory. The nature of the stabilizing interactions was, in particular, assayed using a method recently proposed by the authors to classify the chemical bonds involving the noble-gas atoms. The bond distances and dissociation energies of the investigated ions fall in rather large intervals, and follow regular periodic trends, clearly referable to the difference between the proton affinity (PA) of the various Ng and Ng'. These variations are nicely correlated with the bonding situation of the (Ng-H-Ng)+ and (Ng-H-Ng')+. The Ng-H and Ng'-H contacts range, in fact, between strong covalent bonds to weak, non-covalent interactions, and their regular variability clearly illustrates the peculiar capability of the noble gases to undergo interactions covering the entire spectrum of the chemical bond.

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“…Although the accuracy of the CCSD(T)-F12/aug-cc-pVTZ level of theory has been approved in the literature, it was checked in our previous works (Bop et al 2017b;Bop, Hammami & Faye 2017c).…”

Section: P Ot E N T I a L E N E R G Y S U R Fac E A N D A Na Ly T I C A L F I Tmentioning

confidence: 99%

Potential energy surface and rate coefficients of protonated cyanogen (HNCCN+) induced by collision with helium (He) at low temperature

Bop

Faye

Hammami

2018

Monthly Notices of the Royal Astronomical Society

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Nitriles have been identified in space. Accurately modelling their abundance requires calculations of collisional rate coefficients. These data are obtained by first computing potential energy surfaces (PES) and cross-sections using high accurate quantum methods. In this paper, we report the first interaction potential of the HNCCN + -He collisional system along with downward rate coefficients among the 11 lowest rotational levels of HNCCN + . The PES was calculated using the explicitly correlated coupled cluster approach with simple, second, and non-iterative triple excitation (CCSD(T)-F12) in conjunction with the augmented-correlation consistentpolarized valence triple zeta Gaussian basis set. It presents two local minima of ∼283 and ∼136 cm −1 , the deeper one is located at R = 9 a 0 towards the H end (He• • • HNCCN + ). Using the so-computed PES, we calculated rotational cross-sections of HNCCN + induced by collision with He for energies ranging up to 500 cm −1 with the exact quantum mechanical close coupling method. Downward rate coefficients were then worked out by thermally averaging the cross-sections at low temperature (T ≤ 100 K). The discussion on propensity rules showed that the odd j transitions were favoured. The results obtained in this work may be crucially needed to accurately model the abundance of cyanogen and its protonated form in space.

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Collisional rates based on the first potential energy surface of the NeH+ −He system

Cited by 15 publications

References 51 publications

Hyperfine excitation of NS+ due to para-H2(j = 0) impact

Hyperfine excitation of NS+ due to para-H2(j = 0) impact

On the Proton-Bound Noble Gas Dimers (Ng-H-Ng)+ and (Ng-H-Ng’)+ (Ng, Ng’ = He-Xe): Relationships between Structure, Stability, and Bonding Character

Potential energy surface and rate coefficients of protonated cyanogen (HNCCN+) induced by collision with helium (He) at low temperature

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