Quantum dynamics of the C(D1)+HD and C(D1)+n−D2 reactions on the ã A1′ and b̃ A1″ surfaces

A new global ab initio potential energy surface (called ZMB-a) for the 1(1)A' state of the C((1)D)+H2 reactive system has been constructed. This is based upon ab initio calculations using the internally contracted multireference configuration interaction approach with the aug-cc-pVQZ basis set, performed at about 6300 symmetry unique geometries. Accurate analytical fits are generated using many-body expansions with the permutationally invariant polynomials, except that the fit of the deep well region is taken from our previous fit. The ZMB-a surface is unique in the accurate description of the regions around conical intersections (CIs) and of van der Waals (vdW) interactions. The CIs between the 1(1)A' and 2(1)A' states cause two kinds of barriers on the ZMB-a surface: one is in the linear H-CH dissociation direction with a barrier height of 9.07 kcal/mol, which is much higher than those on the surfaces reported before; the other is in the C((1)D) collinearly attacking H2 direction with a barrier height of 12.39 kcal/mol. The ZMB-a surface basically reproduces our ab initio calculations in the vdW interaction regions, and supports a linear C-HH vdW complex in the entrance channel, and two vdW complexes in the exit channel, at linear CH-H and HC-H geometries, respectively.

Section: Introductioncontrasting

confidence: 57%

Global analytical ab initio ground-state potential energy surface for the C(1D)+H2 reactive system

Zhang

Shen

et al. 2014

“…This is obtained using the C 2v (M) group everywhere 14 or the C 2v one in the reactant channel for T-shaped configurations. 16 Finally, the electronicresolved thermal rates k a and k b are calculated via separated para-H 2 and ortho-H 2 Boltzmann statistics, including the nuclear-spin weights, and the overall thermal rate is equal to k = k a + k b .…”

Section: Theory and Calculationsmentioning

confidence: 99%

“…14,16 They also obtained CD+H/CH+D branching ratio (1.6 ± 0.1) and their respective rates at 300 K. In 2004 and 2005, Balucani et al 7,17 obtained product angular and velocity distributions for the reactions of carbon atoms with H 2 and D 2 using crossed molecular beams.…”

Section: Introductionmentioning

confidence: 96%

Nonadiabatic quantum dynamics of C(1D)+H2→CH+H: Coupled-channel calculations including Renner-Teller and Coriolis terms

Defazio

Bussery‐Honvault

Honvault

et al. 2011

Self Cite

The Renner-Teller (RT) coupled-channel dynamics for the C((1)D)+H(2)(X(1)Σ(g) (+))→CH(X(2)Π)+H((2)S) reaction has been investigated for the first time, considering the first two singlet states ã̃(1)A' and b(1)A'' of CH(2) dissociating into the products and RT couplings, evaluated through the ab initio matrix elements of the electronic angular momentum. We have obtained initial-state-resolved probabilities, cross sections and thermal rate constants via the real wavepacket method for both coupled electronic states. In contrast to the N((2)D)+H(2)(X(1)Σ(g)(+)) system, RT effects tend to reduce probabilities, cross sections, and rate constants in the low energy range compared to Born-Oppenheimer (BO) ones, due to the presence of a repulsive RT barrier in the effective potentials and to long-lived resonances. Furthermore, contrary to BO results, the rate constants have a positive temperature dependence in the 100-400 K range. The two-state RT rate constant at 300 K, lower than the BO one, remains inside the error bars of the experimental value.

“…20 Later, the ab initio data for the BHL PES were refitted with the reproducing kernel Hilbert space (RKHS) method to remove some spurious features of the original BHL surface, and the refitted surface is a) Electronic mail: bian@iccas.ac.cn denoted as RKHS PES. 21 Quantum mechanical (QM) 18,20,[22][23][24][25][26][27][28][29][30][31] and quasiclassical trajectory (QCT) 9,18,19,21,23,30 methods, as well as statistical models, [32][33][34][35] have been applied to investigate the title reaction using the aforementioned PESs. Although there are other ab initio-based PESs and subsequent dynamical calculations, [36][37][38] the RKHS PES is the most widely used in dynamical studies.…”

Section: Introductionmentioning

confidence: 99%

Quantum mechanical differential and integral cross sections for the C(1D) + H2(ν = 0, j = 0) → CH(ν′, j′) + H reaction

Shen

Cao

Bian

2015

Accurate quantum dynamics calculations for the C((1)D) + H2 reaction are performed using a real wave packet approach with full Coriolis coupling. The newly constructed ZMB-a ab initio potential energy surface [Zhang et al., J. Chem. Phys. 140, 234301 (2014)] is used. The integral cross sections (ICSs), differential cross sections (DCSs), and product state distributions are obtained over a wide range of collision energies. In contrast to previous accurate quantum dynamics calculations on the reproducing kernel Hilbert space potential energy surface, the present total ICS is much larger at low collision energies, yielding larger rate coefficients in better agreement with experiment and with slight inverse temperature dependence. Meanwhile, interesting nonstatistical behaviors in the DCSs are revealed. In particular, the DCSs display strong oscillations with the collision energy; forward biased product angular distribution appears when only small J partial wave contributions are included; alternate forward and backward biases emerge with very small increments of collision energy; and the rotational state-resolved DCSs show strong oscillations with the scattering angle. Nevertheless, the total DCSs can be roughly regarded as backward-forward symmetric over the whole energy range and are in reasonably good agreement with the available experimental measurements.