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  1. Article ; Online: New theoretical investigation of rotational inelastic (de)-excitation of calcium isocyanide CaNC(

    Hachani, Lamia / Khadri, Fehmi / Hammami, Kamel

    Physical chemistry chemical physics : PCCP

    2022  Volume 24, Issue 39, Page(s) 24212–24218

    Abstract: The theoretical study of collisions between atoms and molecules provides a detailed description of the involved mechanisms and greatly contributes to improving atmospheric and astrophysics models. In the present paper, we focus on the new calculation of ... ...

    Abstract The theoretical study of collisions between atoms and molecules provides a detailed description of the involved mechanisms and greatly contributes to improving atmospheric and astrophysics models. In the present paper, we focus on the new calculation of rate coefficients for the first 25 rotational levels of the CaNC molecule in collision with He. A new 2D potential energy surface (2D-PES), for the CaNC-He system, was determined using the single, double and perturbative triple excitation restricted coupled-cluster method [rccsd(t)] and the standard aug-cc-pVQZ basis sets. This PES presents a global minimum with a well depth of -21.93 cm
    Language English
    Publishing date 2022-10-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d2cp02485c
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Rotational (de)-excitation of linear C

    Khadri, Fehmi / Hammami, Kamel

    Physical chemistry chemical physics : PCCP

    2019  Volume 21, Issue 8, Page(s) 4606–4612

    Abstract: Tricarbon monoxide (C3O) is an astrochemically important molecule. It is a probe element for determining the chemical composition of gases in molecular clouds, as C3O is a major intermediate of ion-molecule reactions in the gas phase. For C3O, no ... ...

    Abstract Tricarbon monoxide (C3O) is an astrochemically important molecule. It is a probe element for determining the chemical composition of gases in molecular clouds, as C3O is a major intermediate of ion-molecule reactions in the gas phase. For C3O, no collision coefficients are available in the literature. To estimate the abundance of C3O in a solar cold dark cloud: Taurus Molecular Cloud 1 (TMC-1) and find the range of cloud parameters, some authors used the calculated values for the HC3N molecule, which is isoelectronic and has similar rotational constants. Indeed, the calculation of the rate coefficients of C3O(1Σ+) induced by collision with He is performed for thermal temperatures below 25 K. These calculations are based on a new two-dimensional potential energy surface obtained from the explicitly correlated coupled cluster with a single, double and perturbative triple excitation (ccsd(t)-f12) ab initio approach associated with aug-cc-pVTZ basis sets. The PES was found to have a global minimum at (R = 6.2 Bohr and θ = 73°) with a depth of -53.4 cm-1 below the C3O-He dissociation limit. Using this PES, the integral cross sections are performed in the close-coupling quantum time independant formalism for Ec ≤ 110 cm-1 and J ≤ 12. These cross sections were then averaged at low temperature to obtain the downward rate coefficients. The new collisional data should significantly help the interpretation of interstellar C3O emission lines observed with current and future telescopes. We expect that they will allow the accurate determination of the C3O abundance in the interstellar medium, which is crucial to understand the chemistry of carbon chain species in the interstellar gas.
    Language English
    Publishing date 2019-02-11
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c8cp07409g
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Potential Energy Surface for the CH

    Sahnoun, Emna / Wiesenfeld, Laurent / Hammami, Kamel

    The journal of physical chemistry. A

    2020  Volume 124, Issue 16, Page(s) 3242–3248

    Abstract: Methane is an ubiquitous molecule, present as a minor component in many environments, including the Earth and planet atmospheres. Its van der Waals interaction with the main gases is an important ingredient for the understanding of radiative properties ... ...

    Abstract Methane is an ubiquitous molecule, present as a minor component in many environments, including the Earth and planet atmospheres. Its van der Waals interaction with the main gases is an important ingredient for the understanding of radiative properties for those atmospheres. We present here the first precise determination of the interaction between CH
    Language English
    Publishing date 2020-04-13
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.9b10499
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Dynamics of AlOH inelastic scattering with p-H

    Naouai, Manel / Najar, Faouzi / Hammami, Kamel

    Physical chemistry chemical physics : PCCP

    2019  Volume 21, Issue 36, Page(s) 20137–20143

    Abstract: Alkali aluminum hydroxide, AlOH, has associated features with the chemistry of aluminum-bearing species and generally with metal hydroxide molecules in the interstellar clouds where it has been observed. The aim of this work is to obtain accurate ... ...

    Abstract Alkali aluminum hydroxide, AlOH, has associated features with the chemistry of aluminum-bearing species and generally with metal hydroxide molecules in the interstellar clouds where it has been observed. The aim of this work is to obtain accurate rotational rate coefficients of AlOH colliding with the most abundant molecular species in the interstellar medium (ISM), H2, in its lowest rotational state p-H2(J = 0) for the kinetic temperature range 5-80 K. A full and accurate 4D-PES was generated using explicitly correlated coupled cluster with single, double and perturbative triple excitation CCSD(T)-F12a augmented by the aVTZ basis set. Both the close coupling CC and coupled states CS techniques were used to generate rotational cross-sections for AlOH-p-H2 including 13 rotational states (J1 = 0,…,12) for the AlOH molecule and the J2 = 0 state for the H2 molecule for energy thresholds up to E = 500 cm-1. Propensity rules that favor odd ΔJ1 transitions are found all over the temperature range. Further, a comparison of the present AlOH-p-H2(J = 0) rate coefficients with scaled AlOH-He rates was made, revealing mainly good agreement with some discrepancies appearing for large ΔJ1. The use of the present rates is viewed to be a good tool to estimate the aluminum hydroxide abundance.
    Language English
    Publishing date 2019-09-04
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c9cp04214h
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: van der Waals interaction of HNCO and H

    Sahnoun, Emna / Wiesenfeld, Laurent / Hammami, Kamel / Jaidane, Nejmeddine

    The journal of physical chemistry. A

    2018  Volume 122, Issue 11, Page(s) 3004–3012

    Abstract: Isocyanic acid (HNCO) is the most stable of all its isomers; it has been observed repeatedly in many different conditions of the Interstellar Media, and its chemistry is poorly known. To quantitatively estimate the abundance of HNCO with respect to other ...

    Abstract Isocyanic acid (HNCO) is the most stable of all its isomers; it has been observed repeatedly in many different conditions of the Interstellar Media, and its chemistry is poorly known. To quantitatively estimate the abundance of HNCO with respect to other organic molecules, we compute its rotational quenching rates colliding with H
    Language English
    Publishing date 2018-03-22
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.8b00150
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Rotationally inelastic dynamics of LiH (X(1)Σ(+), v = 0) in collisions with Ar: State-to-state inelastic rotational rate coefficients.

    Niane, Aliou / Dath, Cheikh Amadou Bamba / Faye, Ndèye Arame Boye / Hammami, Kamel / Jaidane, Nejm-Eddine

    SpringerPlus

    2014  Volume 3, Page(s) 188

    Abstract: A theoretical study of rotational collision of LiH(X(1)Σ(+),v = 0, J) with Ar has been carried out. The ab initio potential energy surface (PES) describing the interaction between the Ar atom and the rotating LiH molecule has been calculated very ... ...

    Abstract A theoretical study of rotational collision of LiH(X(1)Σ(+),v = 0, J) with Ar has been carried out. The ab initio potential energy surface (PES) describing the interaction between the Ar atom and the rotating LiH molecule has been calculated very accurately and already discussed in our previous work [Computational and Theoretical Chemistry 993 (2012) 20-25]. This PES is employed to evaluate the de-excitation cross sections. The ab initio PES for the LiH(X(1)Σ(+))-Ar((1)S) Van der waals system is calculated at the coupled-cluster [CCSD(T)] approximation for a LiH length fixed to an experimental value of 3.0139 bohrs. The basis set superposition error (BSSE) is corrected and the bond functions are placed at mid-distance between the center of mass of LiH and the Ar atom. The cross sections are then derived in the close coupling (CC) approach and rate coefficients are inferred by averaging these cross sections over a Maxwell-Boltzmann distribution of kinetic energies. The 11 first rotational levels of rate coefficients are evaluated for temperatures ranging from 10 to 300 K. We notice that the de-excitation rate coefficients appear large in the order 10(-10) cm(-3) s(-1) and show very low temperature dependence. The rate coefficients magnify significantly the propensity toward ∆ J = -1 transitions. These results confirm the same propensity already noted for the cross sections.
    Language English
    Publishing date 2014-04-14
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2661116-8
    ISSN 2193-1801
    ISSN 2193-1801
    DOI 10.1186/2193-1801-3-188
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: On the accuracy of explicitly correlated methods to generate potential energy surfaces for scattering calculations and clustering: application to the HCl-He complex.

    Ajili, Yosra / Hammami, Kamel / Jaidane, Nejm Eddine / Lanza, Mathieu / Kalugina, Yulia N / Lique, François / Hochlaf, Majdi

    Physical chemistry chemical physics : PCCP

    2013  Volume 15, Issue 25, Page(s) 10062–10070

    Abstract: We closely compare the accuracy of multidimensional potential energy surfaces (PESs) generated by the recently developed explicitly correlated coupled cluster (CCSD(T)-F12) methods in connection with the cc-pVXZ-F12 (X = D, T) and aug-cc-pVTZ basis sets ... ...

    Abstract We closely compare the accuracy of multidimensional potential energy surfaces (PESs) generated by the recently developed explicitly correlated coupled cluster (CCSD(T)-F12) methods in connection with the cc-pVXZ-F12 (X = D, T) and aug-cc-pVTZ basis sets and those deduced using the well-established orbital-based coupled cluster techniques employing correlation consistent atomic basis sets (aug-cc-pVXZ, X = T, Q, 5) and extrapolated to the complete basis set (CBS) limit. This work is performed on the benchmark rare gas-hydrogen halide interaction (HCl-He) system. These PESs are then incorporated into quantum close-coupling scattering dynamical calculations in order to check the impact of the accuracy of the PES on the scattering calculations. For this system, we deduced inelastic collisional data including (de-)excitation collisional and pressure broadening cross sections. Our work shows that the CCSD(T)-F12/aug-cc-pVTZ PES describes correctly the repulsive wall, the van der Waals minimum and long range internuclear distances whereas cc-pVXZ-F12 (X = D,T) basis sets are not diffuse enough for that purposes. Interestingly, the collision cross sections deduced from the CCSD(T)-F12/aug-cc-pVTZ PES are in excellent agreement with those obtained with CCSD(T)/CBS methodology. The position of the resonances and the general shape of these cross sections almost coincide. Since the cost of the electronic structure computations is reduced by several orders of magnitude when using CCSD(T)-F12/aug-cc-pVTZ compared to CCSD(T)/CBS methodology, this approach can be recommended as an alternative for generation of PESs of molecular clusters and for the interpretation of accurate scattering experiments as well as for a wide production of collisional data to be included in astrophysical and atmospherical models.
    Language English
    Publishing date 2013-07-07
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c3cp44708a
    Database MEDical Literature Analysis and Retrieval System OnLINE

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