The rotational excitation of carbon monoxide by hydrogen atom impact

1975 ◽  
Vol 342 (1629) ◽  
pp. 191-207 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Cross Sections ◽  
Rate Coefficients ◽  
Rotational Degree ◽  
Rotational Excitation ◽  
Body Frame ◽  
Hydrogen Atoms ◽  
Close Coupling ◽  
Coupling Methods ◽  
Low Energies

A quantal study is carried out of the rotational excitation of carbon monoxide in collision with hydrogen atoms. The interaction potential at short range is constructed semi-empirically and joined to the Buckingham potential at long range. The close-coupling formulation is used to assess the reliability of the fixed-nuclei approximation, which is developed in terms of the adiabatic theory of electron-molecule scattering. The applicability of two simplified close-coupling formulations, introduced by Rabitz and by McGuire & Kouri, is examined. We found that the fixed nuclei method is unpromising at low energies and time-consuming at high energies. The two simplified close-coupling methods are capable of providing results of useful accuracy. The similarity in formulation of the fixed-nuclei and one of the close-coupling methods, both of which are body-frame treatments, and the differences in their results show that the rotational degree of freedom must be treated rigorously. The method of Rabitz is economical, and we adopted it to calculate the energy dependent rotation excitation cross sections for the scattering of H + CO. The results are presented in the form of Maxwellian-averaged rate coefficients in the temperature range of 5-150 K.

scholarly journals Electron capture in slow collisions of O6+ions with atomic hydrogen

2019 ◽  
Vol 625 ◽  
pp. A29
Author(s):  
Xiaohe Lin ◽  
Yong Wu ◽  
J. G. Wang ◽  
Bin Shao ◽  
R. K. Janev
Keyword(s):  
Electron Capture ◽  
Cross Sections ◽  
Ground State ◽  
Atomic Hydrogen ◽  
Theoretical Data ◽  
Rate Coefficients ◽  
Hydrogen Atoms ◽  
Close Coupling ◽  
Radiative Transitions ◽  
Reaction Channels

Aims. Electron capture in collisions of highly charged O6+ions with ground-state hydrogen atoms is a very important process in solar wind X-ray studies.Methods. In the present study, the full quantum-mechanical molecular-orbital close-coupling method is employed to study electron capture reactions in collisions of O6+ion with ground-state atomic hydrogen in the energy region from 10−4keV u−1to 5 keV u−1. The ab initio multi-reference single- and double-excitation configuration interaction (MRD-CI) method is used to calculate the potential and coupling data used in the QMOCC calculations.Results. Total and state-selective cross sections for the dominant and subdominant reaction channels are calculated and compared with the available experimental and theoretical data. The branching ratios for Lithium-like O5+excited ions are used to calculate the contribution of cascade radiative transitions fromn = 5 levels to the population of 4l states. From the calculated cross sections, reaction rate coefficients are obtained for temperatures between 1000 and 1 × 109K and compared with other calculations.

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.

Inelastic rate coefficients for collisions of C4H− with H2

2021 ◽  
Author(s):  
Christian Balança ◽  
Ernesto Quintas-Sánchez ◽  
Richard Dawes ◽  
Fabien Dumouchel ◽  
François Lique ◽  
...  
Keyword(s):  
Cross Sections ◽  
Rotational Level ◽  
Carbon Chain ◽  
Rate Coefficients ◽  
Thermodynamical Equilibrium ◽  
Close Coupling ◽  
State Approximation ◽  
Explicitly Correlated ◽  
State Rate ◽  
Chemical Conditions

Abstract Carbon-chain anions were recently detected in the interstellar medium. These very reactive species are used as tracers of the physical and chemical conditions in a variety of astrophysical environments. However, the Local Thermodynamical Equilibrium conditions are generally not fulfilled in these environments. Therefore, collisional as well as radiative rates are needed to accurately model the observed emission lines. We determine in this work the state-to-state rate coefficients of C4H− in collision with both ortho- and para-H2. A new ab initio 4D potential energy surface was computed using explicitly-correlated coupled cluster procedures. This surface was then employed to determine rotational excitation and de-excitation cross sections and rate coefficients for the first 21 rotational levels (up to rotational level j1 = 20) using the close-coupling method, while the coupled-state approximation was used to extend the calculations up to j1 = 30. State-to-state rate coefficients were obtained for the temperature range 2–100 K. The differences between the ortho- and para-H2 rate coefficients are found to be small.

Relaxation of NO+ by collision with para-H2 (j = 0)

2020 ◽  
Vol 494 (1) ◽  
pp. 129-134
Author(s):  
L D Cabrera-González ◽  
D Páez-Hernández ◽  
O Denis-Alpizar
Keyword(s):  
Cross Sections ◽  
Reproducing Kernel ◽  
Reproducing Kernel Hilbert Space ◽  
Rate Coefficients ◽  
Local Thermal Equilibrium ◽  
Large Set ◽  
Close Coupling ◽  
Rotational States ◽  
Scaling Procedure ◽  
Collisional Rate Coefficients

ABSTRACT The first tentative detection of the nitrosylium ion (NO+) in the interstellar medium (ISM) was reported just a few years ago. The application of non-local thermal equilibrium models requires the knowledge of the collisional rate coefficients with the most common colliders in the ISM (e.g. He, H, H2, and e). The main goals of this paper are to study the collision of the NO+ molecule with para-H2 (j = 0) and report the rate coefficients for the lower rotational states of NO+. A large set of ab initio energies was computed at the CCSD(T)/aug-cc-pV5Z level of theory. A new potential energy surface averaged over the H2 orientations was then fitted using a reproducing kernel Hilbert space procedure. The state-to-state cross-sections of NO++para-H2 (j = 0) for the first 18 rotational levels were computed using the close-coupling method. The rotational rate coefficients of this system were compared with those for NO++He, and a different propensity rule was found. Furthermore, the hyperfine rate coefficients were also calculated using the infinite-order-sudden scaling procedure.

Hyperspherical close-coupling calculations for charge-transfer cross sections inHe2++H(1s)collisions at low energies

2003 ◽  
Vol 67 (5) ◽  
Author(s):  
Chien-Nan Liu ◽  
Anh-Thu Le ◽  
Toru Morishita ◽  
B. D. Esry ◽  
C. D. Lin
Keyword(s):  
Charge Transfer ◽  
Cross Sections ◽  
Close Coupling ◽  
Low Energies
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