scholarly journals Rotational quenching of HD induced by collisions with H2 molecules

2019 ◽  
Vol 488 (1) ◽  
pp. 381-386
Author(s):  
Yier Wan ◽  
N Balakrishnan ◽  
B H Yang ◽  
R C Forrey ◽  
P C Stancil
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Cross Sections ◽  
Energy Surface ◽  
Rate Coefficients ◽  
Quantum Mechanical ◽  
Cooling Efficiency ◽  
Close Coupling ◽  
Rotational Transitions ◽  
Good Agreement

ABSTRACT Rate coefficients for rotational transitions in HD induced by H2 impact for rotational levels of HD j ≤ 8 and temperatures 10 K ≤ T ≤ 5000 K are reported. The quantum mechanical close-coupling (CC) method and the coupled-states (CS) decoupling approximation are used to obtain the cross-sections employing the most recent highly accurate H2–H2 potential energy surface (PES). Our results are in good agreement with previous calculations for low-lying rotational transitions The cooling efficiency of HD compared with H2 and astrophysical applications are briefly discussed.

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.

Ab initiodynamics of the He + H+2→ HeH++H reaction: a new potential energy surface and quantum mechanical cross-sections

2000 ◽  
Vol 98 (21) ◽  
pp. 1835-1849 ◽  
Author(s):  
P. PALMIERI ◽  
C. PUZZARINI ◽  
V. AQUILANTI ◽  
G. CAPECCHI ◽  
S. CAVALLI ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Cross Sections ◽  
Energy Surface ◽  
Quantum Mechanical

scholarly journals Rotational de-excitation of tricarbon monosulfide (C3S) in collision with (He): potential energy surface and rates

2020 ◽  
Vol 365 (12) ◽  
Author(s):  
E. Sahnoun ◽  
M. Ben Khalifa ◽  
F. Khadri ◽  
K. Hammami
Keyword(s):  
Potential Energy ◽  
Interstellar Medium ◽  
Potential Energy Surface ◽  
Cross Sections ◽  
Energy Surface ◽  
Accurate Determination ◽  
Carbon Chain ◽  
Basis Sets ◽  
Rate Coefficients

AbstractDespite that the tricarbon monosulfide (C3S) is among the first sulfur-containing carbon-chain molecules to be detected in the interstellar medium, no studies focused on the determination of its collisional rates. These rate coefficients are essential to estimate the abundance of C3S in the interstellar medium. Computations of the C3S($^{1}\Sigma^{+}$ Σ + 1 ) downward rate coefficients, induced by collision with He, are performed by averaging the integral cross sections at low temperature (below $25~\text{K}$ 25 K ). Calculations of the cross sections in the close-coupling quantum time independent formalism for $E_{c}\leq110~\text{cm}^{-1}$ E c ≤ 110 cm − 1 and $J\leq10$ J ≤ 10 are based on a new 2-D potential energy surface. This PES is obtained from the explicit correlated coupled cluster with a single, double and perturbative triple excitation [ccsd(t)-f12] ab initio approach and the aug-cc-pVTZ basis sets. The PES have a global minimum of $-55.69~\text{cm}^{-1}$ − 55.69 cm − 1 located at $R=6.25$ R = 6.25 bohr and $\theta=94^{\circ}$ θ = 94 ∘ , and a second minimum of $-36.95~\text{cm}^{-1}$ − 36.95 cm − 1 at $R=9.35$ R = 9.35 bohr and $\theta=0^{\circ}$ θ = 0 ∘ . A comparison of C3S rates with those of the isoelectronic molecule C3O was made. The results indicate a great temperature dependence of the rates for transitions of $\Delta J>2$ Δ J > 2 . We expect that the new collisional data will allow for accurate determination of the C3S abundance in several interstellar regions.

Rotational excitation of HNCO by He: potential energy surface, collisional cross-sections and rate coefficients

2017 ◽  
Vol 471 (1) ◽  
pp. 80-88 ◽  
Author(s):  
E. Sahnoun ◽  
Y. Ajili ◽  
K. Hammami ◽  
N.-E. Jaidane ◽  
M. Mogren Al Mogren ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Cross Sections ◽  
Energy Surface ◽  
Rate Coefficients ◽  
Rotational Excitation

Intermolecular configurations dominated by quadrupole–quadrupole electrostatic interactions: explicit correlation treatment of the five-dimensional potential energy surface and infrared spectra for the CO–N2 complex

2018 ◽  
Vol 20 (3) ◽  
pp. 2036-2047 ◽  
Author(s):  
Jing-Min Liu ◽  
Yu Zhai ◽  
Xiao-Long Zhang ◽  
Hui Li
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Infrared Spectra ◽  
Electrostatic Interactions ◽  
Energy Surface ◽  
Experimental Results ◽  
Intermolecular Potential ◽  
Quantum Mechanical ◽  
Explicit Correlation ◽  
Good Agreement

Quantum mechanical average over rovibrational wavefunction based on new intermolecular potential energy surface has been done to get molecular alignment for CO–N2 complex, which is in good agreement with experimental results.

scholarly journals Quantum Dynamics of Rotational Transitions in CN (X2Σ+) by H+ Collisions

2021 ◽  
Vol 9 ◽  
Author(s):  
Bhargava Anusuri ◽  
T. J. Dhilip Kumar ◽  
Sanjay Kumar
Keyword(s):  
Cross Sections ◽  
Quantum Dynamics ◽  
Energy Surface ◽  
Theoretical Calculations ◽  
Rate Coefficients ◽  
Quantum Mechanical ◽  
Microwave Background ◽  
Close Coupling ◽  
Proton Collisions ◽  
Interstellar Media

Collisional cross-sections of inelastic rotational excitations of CN in its ground electronic state (X2Σ+) by H+ scattering are studied by the exact quantum mechanical close-coupling (CC) method at very low collision energies (0–600 cm−1) relevant to interstellar atmospheres. Ab initio rigid rotor potential energy surface computed at MRCI/cc-pVTZ level of accuracy has been employed. Rate coefficients for the rotational excitations have also been calculated. The obtained results are compared with previous theoretical calculations and analyzed whether proton collisions could be significant sources for rotationally excited CN as a possible source for cosmic microwave background of about 3 K from the interstellar media.

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