Collision excitation of sodium cyanide molecule by helium at low temperature

2019 ◽  
Vol 489 (3) ◽  
pp. 4322-4328
Author(s):  
C Gharbi ◽  
Y Ajili ◽  
D Ben Abdallah ◽  
M Mogren Al Mogren ◽  
M Hochlaf
Keyword(s):  
Electronic Structure ◽  
Cross Sections ◽  
Energy Surface ◽  
Three Dimensional ◽  
Sodium Cyanide ◽  
Rate Coefficients ◽  
Quantum Scattering ◽  
Stable Form ◽  
Excitation Cross Sections ◽  
Order Of Magnitude

ABSTRACT Cyanides/isocyanides are the most common metal-containing molecules in interstellar medium. In this work, quantum scattering calculations were carried out to determine the rotational (de-)excitation cross-sections of the most stable form of the sodium cyanide molecule, t-NaCN, in collision with the helium atom. Rate coefficients for the first 43 rotational levels (up to ${j_{{K_a}{K_c}}}$ = 63,3) of NaCN were determined for kinetic temperatures ranging from 1 to 30 K. Prior to that, we constructed a new three-dimensional potential energy surface (3D-PES) for the t-NaCN–He interacting system. These electronic structure computations are done at the CCSD(T)-F12/aug-cc-pVTZ level of theory. Computations show the dominance of Δj = ΔKc = −1 transitions, which is related to the dissymmetric shape of the t-NaCN–He 3D-PES. The NaCN–He rate coefficients are of the same order of magnitude (∼10−11 cm3.s−1) as those of other metal CN-containing molecules such as MgCN and AlCN in collision with He. This work is a contribution for understanding and modelling the abundances and chemistry of nitriles in astrophysical media.

Rotational de-excitations of C3H+ (1Σ+) by collision with He: new ab initio potential energy surface and scattering calculations

2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Energy Surface ◽  
Molecular Ions ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Collisional Rate Coefficients

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

Inelastic scattering of interstellar silyl cyanide (SiH3CN) by helium atoms : cross-sections and rate coefficients for A- and E-SiH3CN

2021 ◽  
Vol 507 (4) ◽  
pp. 5264-5271
Author(s):  
Manel Naouai ◽  
Abdelhak Jrad ◽  
Ayda Badri ◽  
Faouzi Najar
Keyword(s):  
Inelastic Scattering ◽  
Total Energy ◽  
Cross Sections ◽  
Three Dimensional ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Explicitly Correlated ◽  
Correlation Consistent ◽  
Triple Excitation

ABSTRACT Rotational inelastic scattering of silyl cyanide (SiH3CN) molecule with helium (He) atoms is investigated. Three-dimensional potential energy surface (3D-PES) for the SiH3CN–He interacting system is carried out. The ab initio 3D-PES is computed using explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation CCSD(T)-F12a connected to augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. A global minimum at (R = 6.35 bohr; θ = 90○; ϕ = 60○) with a well depth of 52.99 cm−1 is pointed out. Inelastic rotational cross-sections are emphasized for the 22 first rotational levels for total energy up to 500 cm−1 via close coupling (CC) approach in the case of A-SiH3CN and for the 24 first rotational levels for total energy up to 100 cm−1 via CC and from 100 to 500 cm−1 via coupled states (CS) in the case of E-SiH3CN. Rate coefficients are derived for temperature until 80 K for both A- and E-SiH3CN–He systems. Propensity rules are obtained for |ΔJ| = 2 processes with broken parity for A-SiH3CN and for |ΔJ| = 2 processes with |ΔK| = 0 and unbroken parity for E-SiH3CN.

Rate coefficients for rotationally inelastic collisions of CO with H2

2001 ◽  
Vol 79 (2-3) ◽  
pp. 589-595 ◽  
Author(s):  
M Mengel ◽  
F C De Lucia ◽  
E Herbst
Keyword(s):  
Potential Energy ◽  
Energy Surface ◽  
Potential Surface ◽  
Chem Phys ◽  
Inelastic Collisions ◽  
Rate Coefficients ◽  
Quantum Scattering ◽  
Collision System ◽  
Pressure Broadening ◽  
Experimental Pressure

We have performed quantum-scattering calculations to determine inelastic rate coefficients of the astrophysically important collision system CO–H2. We have used a modified version of the most recent potential-energy surface by Jankowski and Szalewicz (J. Chem. Phys. 108, 3554 (1998)), which has been proven to be superior to a previous potential surface by comparison with experimental pressure broadening data. In contrast to previous studies we find that inelastic rates with Δ J = 2 for CO are smaller than those with Δ J = 1. PACS No.: 34.50Ez

scholarly journals Theoretical Characterization of Transition State Dynamical Resonances in Heavy–Light–Heavy Reactions

1991 ◽  
Vol 11 (3-4) ◽  
pp. 291-302
Author(s):  
A. Aguilar ◽  
M. Albertí ◽  
R. Blasco ◽  
M. Gilibert ◽  
X. Giménez ◽  
...  
Keyword(s):  
Transition State ◽  
Cross Sections ◽  
Energy Surface ◽  
Three Dimensional ◽  
Direct Consequence ◽  
Resonant Peak ◽  
S Matrix ◽  
Energy Dependent ◽  
Argand Plot

The resonant reactivity of three elementary Heavy–Light–Heavy reactions is presented and discussed. Collinear reactivity, in which a vibrational adiabatic model is constructed, is used for a detailed analysis of resonance phenomena, which appear as a direct consequence of transition state metastable states in the strong interaction region of the potential energy surface. Their influence on the detailed mechanism of the elementary process is also discussed. The shape of the resonant peak, and the phase and the Argand plot of the S-matrix are used for a further characterization.Three-dimensional approximate calculations are used to test the evolution of the energy dependent structure present in detailed quantities when sums and integrations over all partial waves contributing to reaction are taken into account to obtain the usual averaged global quantities such as integral state-to-state cross sections.

scholarly journals Astrophysically motivated laboratory measurements of deuterium reacting with isotopologues of H

2019 ◽  
Vol 15 (S350) ◽  
pp. 114-115
Author(s):  
K. P. Bowen ◽  
P.-M. Hillenbrand ◽  
J. Liévin ◽  
X. Urbain ◽  
D. W. Savin
Keyword(s):  
Cross Sections ◽  
Zero Point ◽  
Rate Coefficients ◽  
Laboratory Measurements ◽  
Exchange Reactions ◽  
Point Energy ◽  
Chemical Tracers ◽  
Prestellar Cores ◽  
Order Of Magnitude ◽  
High Level

AbstractH2D+ and D2H+ are important chemical tracers of prestellar cores due to their pure rotational spectra that can be excited at the ~20 K temperature of these environments. The use of these molecules as probes of prestellar cores requires understanding the chemistry that forms and destroys these molecules. Of the eight key reactions that have been identified (Albertssonet al. 2013), five are thought to be well understood. The remaining three are the isotope exchange reactions of atomic D with H $${ + \over 3}$$ , H2D+, and D2H+. Semi-classical results differ from the classical Langevin calculations by an order of magnitude (Moyano et al. 2004). To resolve this discrepancy, we have carried out laboratory measurements for these three reactions. Absolute cross sections were measured using a dual-source, merged fast-beams apparatus for relative collision energies between ~10 meV to ~10 eV (Hillenbrand et al. 2019). A semi-empirical model was developed incorporating high level quantum mechanical ab initio calculations for the zero-point-energy-corrected potential energy barrier in order to generate thermal rate coefficients for astrochemical models. Based on our studies, we find that these three reactions proceed too slowly at prestellar core temperatures to play a significant role in the deuteration of H $${ + \over 3}$$ isotopologues.

Collisional excitation of H2S by molecular hydrogen

2020 ◽  
Vol 494 (4) ◽  
pp. 5239-5243
Author(s):  
Paul J Dagdigian
Keyword(s):  
Energy Surface ◽  
Rate Coefficients ◽  
Cluster Method ◽  
Quantum Scattering ◽  
Collisional Excitation ◽  
Close Coupling ◽  
Accurate Knowledge ◽  
Explicitly Correlated ◽  
Collisional Rate Coefficients ◽  
Collisional Rate

ABSTRACT Accurate estimates of the abundance of H2S, and inferences about the unmeasured H2 density, require accurate knowledge of radiative and collisional rate coefficients. Time-independent close-coupling quantum scattering calculations have been employed to compute rate coefficients for (de-)excitation of para- and ortho-H2S in collisions with para- and ortho-H2. These calculations utilized a potential energy surface for the interaction of H2S with H2 recently computed by the explicitly correlated CCSD(T)-F12a coupled-cluster method. Rate coefficients for temperatures ranging from 5 to 500 K were calculated for all transitions among the first 19 rotational levels of H2S, whose energies are less than or equal to 405 K. These rate coefficients are compared with previous estimates of these quantities.

QUANTUM DYNAMICS OF THE He + Li2 INELASTIC SCATTERING

2011 ◽  
Vol 10 (03) ◽  
pp. 297-307
Author(s):  
SINAN AKPINAR ◽  
TUNAY TURMUS ◽  
SEDA SURUCU
Keyword(s):  
Wave Packet ◽  
Cross Sections ◽  
Quantum Dynamics ◽  
Total Angular Momentum ◽  
Collision Energy ◽  
Energy Surface ◽  
Transition Probabilities ◽  
Three Dimensional ◽  
Quantum Wave ◽  
Inelastic Reaction

In this paper, we report the results of three dimensional time dependent quantum wave packet calculations carried out for He+Li2 inelastic reaction in the collision energy range 0.43–1.18 eV. A three dimensional potential energy surface (PES) computed by Varandas was used for the dynamical calculations.1 The state to state and state to all transition probabilities for total angular momentum J = 0 have been calculated in a broad range of collision energies. Integral cross-sections and rate constants have been calculated from the wave packet transition probabilities by means of J-shifting approximation based on a capture model and a uniform J-shifting method for J > 0.

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