Significant nonadiabatic effects in the C + CH reaction dynamics

Abstract

Rigorous quantum nonadiabatic calculations are carried out on the two coupled electronic states (1(2)A' and 2(2)A') for the C + CH reaction. For all calculations, the initial wave packet was started from the entrance channel of the 1(2)A' state and the initial state of the CH reactant was kept in its ground rovibrational state. Reaction probabilities for total angular momenta J from 0 to 160 are calculated to obtain the integral cross section over an energy range from 0.005 to 0.8 eV collision energy. Significant nonadiabatic effects are found in the reaction dynamics. The branching ratio of the ground state and excited state of C(2) produced is around 0.6, varying slightly with the collision energy. Also, a value of 2.52 × 10(-11) cm(3) molecule(-1) s(-1) for the state selected rate constant k (v = 0, j = 0) at 300 K is obtained, which may be seen as a reference in the future chemical models of interstellar clouds.

On the temperature dependence of the rate coefficient of formation of C$_2^+$ from C + CH+

“…E-mail: srampino@thch.unipg.it in the interstellar medium are neutral-ion and neutral-neutral atomdiatom (A + BC) bimolecular reactions involving carbon and hydrogen atoms (Solomon & Klemperer 1972;Herbst 2001). In order to ground the available information on these processes on rigorous theoretical treatments, in the last fifteen years several studies either based on quasi-classical trajectory (QCT) or quantum-reactivescattering (QRS) techniques have appeared on three-atom systems such as CH 2 (see Bussery-Honvault et al (2001); Lin et al (2004); Balucani et al (2004Balucani et al ( , 2005; Defazio et al (2009) ;Joseph et al (2011); Sun et al (2013); Wu et al (2014) for reaction C + H 2 ), CH + 2 (see Herraez-Aguilar et al (2014) and Zanchet et al (2013) for reaction C + + H 2 and Stoecklin & Halvick (2005) ;Warmbier & Schneider (2011);Bovino et al (2015) for reaction CH + + H), and C 2 H (see Boggio-Pasqua et al (1998); Tang et al (2001b,a); Yang et al (2011) for reaction C + CH). On the contrary, little attention has received the positively charged variant of the latter system, C 2 H + , for which the lowest-energy atom-diatom reaction channel is the exoergic one C ( 3 P 0 ) + CH…”

Time-dependent quantum mechanical wave packet dynamics

“…Much of the complexity arises due to the difficulty in representing the large amplitude molecular motion and asymptotic behaviour in a resonably acceptable diabatic electronic framework. It is only recently that some attempts have been made to investigate the effect of nonadiabatic coupling on photodissociation 26,[270][271][272] and bi-molecular reactive scattering [273][274][275][276][277][278][279][280][281][282][283][284][285][286][287] dynamics. In the following we discuss the developments in the nonadiabatic dynamics study of (R1) in the recent past employing TDQMWP methods.…”

Laser-Driven Isomerization of HCN → HNC: The Importance of Rotational Excitation

“…The application of the time-dependent wave packet method to solve dynamical problems in molecular physics has been successful for the understanding of basic atomic and molecular phenomena. A variety of chemical problems such as photodissociation − and reactive scattering, − have been investigated using the time-dependent quantum wave packet method. The triatomic molecular system is ideally suited for time-dependent quantum calculation because its potential surfaces can be obtained accurately via ab initio calculations.…”