The infinite‐order‐sudden‐approximation calculations of reactive cross sections and product angular distributions for the F+H2 reaction and its isotopic variants on a modified London–Eyring–Polanyi–Sato potential energy surface

1990 ◽  
Vol 93 (4) ◽  
pp. 2487-2492 ◽  
Author(s):  
Toshiyuki Takayanagi ◽  
Shigeru Tsunashima ◽  
Shin Sato

1994 ◽  
Vol 72 (3) ◽  
pp. 985-994 ◽  
Author(s):  
James J. C. Barrett ◽  
Howard R. Mayne ◽  
Mark Keil ◽  
Leslie J. Rawluk

"Exact" quantum close coupled (CC) and infinite-order sudden approximation (IOSA) calculations have been carried out for the Ar + HF system on an accurate potential energy surface. The differential cross sections from the IOSA calculations show marked differences from the CC results. We find that the energy sudden component of the IOSA breaks down in a different manner for small and large impact parameters, significantly shifting and distorting the state-to-state differential cross sections. We also find that the centrifugal sudden approximation alone reproduces all features of the full semiclassical calculations quite faithfully. Through the use of several rotational sudden approximations, including a semiclassical version of the IOSA, we identify how the differences between the CC and IOSA results arise.



2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar

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.



2019 ◽  
Vol 15 (S350) ◽  
pp. 443-444
Author(s):  
Jan Franz ◽  
Francesco Antonio Gianturco

AbstractThe cross sections for rotational inelastic collisions between atoms and a molecular anion can be very large, if the anion has a dipole moment. This makes molecular anions very efficient in cooling atomic gases. We address rotational inelastic collisions of Helium atoms with the molecular anion C2N–. Here we present preliminary calculations of the potential energy surface.



1997 ◽  
Vol 107 (3) ◽  
pp. 902-913 ◽  
Author(s):  
Tino G. A. Heijmen ◽  
Tatiana Korona ◽  
Robert Moszynski ◽  
Paul E. S. Wormer ◽  
Ad van der Avoird




2011 ◽  
Vol 135 (2) ◽  
pp. 024301 ◽  
Author(s):  
Alexandre Faure ◽  
Krzysztof Szalewicz ◽  
Laurent Wiesenfeld


2011 ◽  
Vol 10 (02) ◽  
pp. 147-163
Author(s):  
LI ZHANG ◽  
CHAO-YONG ZHU ◽  
GANG JIANG ◽  
CHAOYUAN ZHU ◽  
Z. H. ZHU

A quasiclassical trajectory method was employed to study reaction Ge+H 2 (v=0, j=0) and reverse reaction H+GeH (v=0, j=0) on an analytical potential energy surface obtained from simplified many-body expansion method with fitting to B3P86/CC-pVTZ calculations around a global minimum and a long-range van de Waals well plus spectroscopy data for diatomic molecules GeH and H2 . Reaction probabilities from both reaction and reverse reaction were calculated. Dominant reaction is complex-forming reaction Ge+H2 (v=0, j=0) → GeH2 , and its cross section is 10 times bigger than that of complex-forming reaction from the reverse reaction. There is no threshold effect for complex-forming reaction and the cross sections for both complex-forming reactions decrease with the increase of collision energy. Life time of complex is shown to be decreasing with increase of collision energy. Dominant reverse reaction is reaction H + GeH (v=0,j=0) → Ge+H2 ; the reaction probability decreases with the increase of collision energy and differential cross section shows that this reverse reaction has almost equal angular distribution at low collision energy and mostly forward scattering at high collision energy.





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