Quantum scattering calculations on H2O+H→H2+OH and isotopes: Rotational distributions and cross sections

1993 ◽  
Vol 99 (10) ◽  
pp. 7774-7786 ◽  
Author(s):  
Gunnar Nyman ◽  
David C. Clary
Keyword(s):  
Cross Sections ◽  
Quantum Scattering

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.

scholarly journals The hyperfine excitation of OH radicals by He

2016 ◽  
Vol 70 (4) ◽  
Author(s):  
Sarantos Marinakis ◽  
Yulia Kalugina ◽  
François Lique
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Nuclear Spin ◽  
Energy Surface ◽  
Quantum Scattering ◽  
Oh Radicals ◽  
Vibrational Motion ◽  
Astronomical Observations

Abstract Hyperfine-resolved collisions between OH radicals and He atoms are investigated using quantum scattering calculations and the most recent ab initio potential energy surface, which explicitly takes into account the OH vibrational motion. Such collisions play an important role in astrophysics, in particular in the modelling of OH masers. The hyperfine-resolved collision cross sections are calculated for collision energies up to 2500 cm-1 from the nuclear spin free scattering S-matrices using a recoupling technique. The collisional hyperfine propensities observed are discussed. As expected, the results from our work suggest that there is a propensity for collisions with ΔF = Δj. The new OH−He hyperfine cross sections are expected to significantly help in the modelling of OH masers from current and future astronomical observations. Graphical abstract

Collisional (de-)excitation of protonated cyanoacetylene (HC3NH+) by helium at low and moderate temperatures

2021 ◽  
Vol 503 (2) ◽  
pp. 2902-2912
Author(s):  
M Mogren Al Mogren ◽  
D Ben Abdallah ◽  
S Dhaif Allah Al Harbi ◽  
M S Al Salhi ◽  
M Hochlaf
Keyword(s):  
Cross Sections ◽  
Quantum Scattering ◽  
Thermodynamical Equilibrium ◽  
Close Coupling ◽  
Molecular Chemistry ◽  
Excitation Cross Sections ◽  
Non Local ◽  
Total Energies ◽  
Highly Correlated ◽  
Local Thermodynamical Equilibrium

ABSTRACT Protonated cyanoacetylene, HC3NH+, is detected in astrophysical media, where it plays a key role as an intermediate in the chemistries of HCN/HNC and of cyanopolyynes. We first generated a potential energy surface (PES) describing the intermonomer interaction between HC3NH+ and He in Jacobi coordinates using the highly correlated CCSD(T)-F12/aug-cc-pVTZ ab initio methodology. Then, scattering calculations based on an exact close-coupling quantum-scattering technique were done to obtain pure rotational cross-sections for the rotational (de-)excitation of HC3NH+ after collision with He for total energies up to 2500 cm−1. These cross-sections are used to deduce the collision rates in the 5–350 K temperature range for the low-lying rotational levels of HC3NH+ (up to $j\,\, = \,\,15$). In addition, we generated an average PES for the HC3NH+–H2 system. The preliminary results show that the H2($j_{\mathrm{H_2}} = 0$) and He state-to-state de-excitation cross-sections have similar magnitudes, even though the H2 cross-sections are larger by a factor of 2–2.5. This work should help with the accurate derivation of protonated cyanoacetylene abundances in non-local thermodynamical equilibrium astrophysical media. These will put more constraints on the chemical pathways involving the formation and destruction of HC3NH+ while going back to the cyanopolyyne family and more generally those parts of nitrogen-containing molecular chemistry.

Observation of Partial Wave Resonances in Low-Energy O2–H2 Inelastic Collisions

Science ◽  
2013 ◽  
Vol 341 (6150) ◽  
pp. 1094-1096 ◽  
Author(s):  
Simon Chefdeville ◽  
Yulia Kalugina ◽  
Sebastiaan Y. T. van de Meerakker ◽  
Christian Naulin ◽  
François Lique ◽  
...  
Keyword(s):  
Partial Wave ◽  
Cross Sections ◽  
Ground State ◽  
Total Angular Momentum ◽  
Inelastic Collisions ◽  
Quantum Mechanical ◽  
Quantum Scattering ◽  
Rotational Excitation ◽  
Collision Processes ◽  
Theoretical Results

Partial wave resonances predicted to occur in bimolecular collision processes have proven challenging to observe experimentally. Here, we report crossed-beam experiments and quantum-scattering calculations on inelastic collisions between ground-state O2 and H2 molecules that provide state-to-state cross sections for rotational excitation of O2 (rotational state N = 1, j = 0) to O2 (N = 1, j = 1) in the vicinity of the thermodynamic threshold at 3.96 centimeter−1. The close agreement between experimental and theoretical results confirms the classically forbidden character of this collision-induced transition, which occurs exclusively in a purely quantum mechanical regime via shape and Feshbach resonances arising from partial waves with total angular momentum (J) = 2 to 4.

QUANTUM SCATTERING OF AN ATOM FROM AN ADSORBED MOLECULE ON A SMOOTH METAL SURFACE

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2457-2464 ◽  
Author(s):  
YUAN-TA TSENG ◽  
KEH-NING HUANG ◽  
KWONG-TIN TANG
Keyword(s):  
Metal Surface ◽  
Cross Sections ◽  
Differential Cross ◽  
Flat Surface ◽  
Adsorbed Molecule ◽  
Quantum Scattering ◽  
Differential Cross Sections ◽  
Surface Integral ◽  
Average Potential ◽  
Better Than

The scattering of He atom from a single CO molecule adsorbed on a smooth metal surface is modeled with an ab initio average potential of He - CO interaction super-imposed on a perfect reflecting flat surface. Integral as well as differential cross sections are obtained from exact quantum mechanical calculations. Rayleigh oscillations are shown to be present in the energy dependence of the integral cross sections. Among many Fraunhoffer and reflection-symmetry oscillations in the differential cross sections, a single peak is identified as the rainbow oscillation. This parameter free calculation can explain the observed integral and differential cross sections better than the previously used hard hemisphere model.

scholarly journals Reaction cross sections and thermal rate constant for Cl− + CH3Br → ClCH3 + Br− from J-dependent quantum scattering calculations

2016 ◽  
Vol 18 (29) ◽  
pp. 19668-19675 ◽  
Author(s):  
Carsten Hennig ◽  
Stefan Schmatz
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
Scattering Theory ◽  
Total Angular Momentum ◽  
Reaction Cross ◽  
Quantum Scattering ◽  
Initial State ◽  
Quantum Scattering Theory ◽  
Reduced Time ◽  
Reaction Cross Sections

Employing dimensionality-reduced time-independent quantum scattering theory and summation over all possible total angular momentum states, initial-state selected reaction cross sections for the exothermic gas-phase bimolecular nucleophilic substitution (SN2) reaction Cl− + CH3Br → ClCH3 + Br− have been calculated.

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