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We carried out accurate quantum wave packet as well as quasi-classical trajectory (QCT) calculations for H + CaCl (νi = 0, ji = 0) reaction occurring on an adiabatic ground state using the recent ab initio potential energy surface to obtain the quantum and QCT reaction probabilities for several partial waves (J = 0, 10, and 20) as well as state resolved QCT integral and differential cross sections. The complete list of vibrational energy levels supported by the intermediate HCaCl complex is also obtained using the Lanczos algorithm. The QCT reaction probabilities show excellent agreement with the quantum ones except for the failure in reproducing the highly oscillatory resonance structure. Despite the fact that the reaction is exothermic and the existence of a barrier that is energetically lower than the bottom of the reactant valley, the reaction probability for J = 0 shows threshold-like behavior and the reactivity all through the energies is very low (＜0.1). The dynamical features at two different energy regions (＜0.35 eV and ＞0.35 eV) are found to be different drastically from each other. The analyses of these results suggest that the reaction is governed by one of the two different types of reaction mechanism, one is the direct mechanism at the high energy region and the other is the indirect mechanism at the low energy region by which the reaction proceeds through the long-lived intermediate complex followed by a statistical dissociation into asymptotic channels. [ABSTRACT FROM AUTHOR]

A computational study for the title reaction is carried out employing recent ab initio potential energy surface. J = 0 reaction probability is obtained using both quasiclassical trajectory (QCT) and wave packet methods. The total and state resolved integral as well as differential cross sections are also obtained by means of QCT method. Dynamics of the title reaction shows qualitative similarity with its isotopic counterpart, the H + CaCl reaction, but quantitatively, reactivity is significantly enhanced in the title reaction. In addition, the effect of initial rotational state excitation on H + CaCl reaction is investigated. [ABSTRACT FROM AUTHOR]

The integral cross sections (ICSs) and rate constants (RCs) for the title reaction are calculated by means of accurate quantum wave packet method employing the recent ab initio potential energy surface developed by Peterson and co-workers. Hundreds of partial wave contributions (up to J=150) are calculated explicitly taking Coriolis coupling into account. The ICSs are found to increase monotonically with energy and their energy dependences are smooth except in the energy range below the potential energy barrier, where several resonance peaks are observed. The temperature dependences of the RCs obey in general the Arrhenius law. These behaviors manifest the dominance of abstract mechanism. Initial rotational state (j i ) excitations are found to greatly enhance the reactivity starting from j i =4, while exhibiting a complicated dependence for j i <4. From Boltzmann average of the initial state specified RCs (for j i =0-15) we obtained thermal RCs which are in reasonable agreement with available experimental results., (© 2024 Wiley-VCH GmbH.)

A global potential energy surface (PES) for the electronic ground state of the Na + HF reactive system is constructed by three-dimensional cubic spline interpolation of 37 000 ab initio points obtained using the multireference configuration interaction method including the Davidson's correction (MRCI + Q) with auc-cc-pV5Z basis set. The endoergicity, well depth and properties of the separated diatomic molecules are in good agreement with experimental estimations. Quantum dynamics calculations have been performed and compared with those of the previous MRCI PES as well as experimental values. The better agreement between theory and experiment indicates the accuracy of the new PES., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The dynamics of the reactive scatterings of the ground (Na(3S)) and first excited (Na(3P)) state sodium atoms from hydrogen fluoride (HF) molecules is investigated by performing comprehensive Coriolis-coupled quantum wave packet calculations on the recent ab initio potential energy surface (PES). In the Na(3S) + HF reaction, the nonadiabatic effect is found to be negligibly small, and the reactivity is significantly promoted by the initial vibrational excitations being in line with the available experimental result. Excellent quantitative agreement between theory and experiment is also achieved for the initial state specified integral cross sections and rate constants for v ≥ 3 vibrational states. However, the calculated rate constant for v = 2 significantly underestimates the experimental result. The possible cause for the disagreement is discussed in detail. For the Na(3P) + HF scattering, which can lead to the formation of either the ground state NaF + H product or Na(3S) + HF reactant via the harpooning process, the calculated result for the integral cross section shows excellent agreement with the available experimental result indicating the reasonable accuracy of the interstate coupling term of the employed PES.