Encontrados 18 documentos, a visualizar página 1 de 2
HN2(2A‘) Electronic Manifold. II. Ab Initio Based Double-Sheeted DMBE Potential...
Mota, Vinícius C.; Varandas, António J. C.A double-sheeted double many-body expansion potential energy surface is reported for the coupled 12A‘/22A‘ states of HN2 by fitting about 6000 ab initio energies. All crossing seams are described to their full extent on the basis of converged results. The lowest adiabatic sheet is fitted with a rmsd of 0.8 kcal mol-1 with respect to the calculated energies up to 100 kcal mol-1 above the absolute minimum, and th...
Vibrational Relaxation of Highly Vibrationally Excited O3 in Collisions with OH
Zhang, Lei; Luo, Pingya; Huang, Zhiyu; Chen, Hong; Varandas, António J. C.We report a theoretical study of highly excited O3 in collisions with vibrationally cold OH. Special emphasis is placed on initial vibrational energies of O3 between 9 and 21 kcal mol−1. All calculations have employed the quasiclassical trajectory method and the realistic double many-body expansion potential energy surface for HO4(2A). Many aspects of the title relaxation process are presented. The results indi...
Application of renormalized coupled-cluster methods to potential function of water
Piecuch, Piotr; Wloch, Marta; Varandas, António J. C.Abstract The goal of this paper is to examine the performance of the conventional and renormalized single-reference coupled-cluster (CC) methods in calculations of the potential energy surface of the water molecule. A comparison with the results of the internally contracted multi-reference configuration interaction calculations including the quasi-degenerate Davidson correction (MRCI(Q)) and the spectroscopica...
HN2(2A‘) Electronic Manifold. I. A Global ab Initio Study of First Two States
Mota, Vinícius C.; Varandas, António J. C.A detailed ab initio multireference configuration interaction calculation with a standard aug-cc-pVTZ basis set is reported for the 12A‘ and 22A‘ states of the title system. The aim is to establish the dissociation scheme of all channels, while revealing the 22A‘/32A‘ seam of conical intersections consistent with the crossings in the diatomic fragments. An ab initio mapping of linear NNH and T-shaped and linear...
Variational transition-state theory study of the atmospheric reaction OH + O3 →...
Ju, Li-Ping; Han, Ke-Li; Varandas, António J. C.We report variational transition-state theory calculations for the OH + O3rarr HO2 + O2 reaction based on the recently reported double many-body expansion potential energy surface for ground-state HO4 [Chem Phys Lett 2000, 331, 474]. The barrier height of 1.884 kcal mol-1 is comparable to the value of 1.77-2.0 kcal mol-1 suggested by experimental measurements, both much smaller than the value of 2.16-5.11 kcal ...
Dynamics Study of the OH + O3 Atmospheric Reaction with Both Reactants Vibratio...
Zhang, Lei; Luo, Pingya; Huang, Zhiyu; Varandas, António J. C.The dynamics of the title five-atom atmospheric reaction is studied by the quasiclassical trajectory method for vibrational states of OH over the range 2 ≤ v ≤ 9 and initial vibrational energies of O3 between 9 and 21 kcal mol-1 using a previously reported double many-body expansion potential energy surface for HO4(2A). The results show that the reaction is controlled by both capture- and barrier-type mechanism...
Ro-Vibrational States of Triplet H2D
Alijah, Alexander; Varandas, António J. C.We present rotational term values for J ≤ 3 of the vibrational states with up to twofold excitation of H2D+ in the lowest electronic triplet state (a3 ). The calculations were performed using the method of hyperspherical harmonics and our recent accurate double many-body expansion potential energy surface. ; http://dx.doi.org/10.1021/jp0565709
A Quantum Wave Packet Dynamics Study of the N(2D) + H2 Reaction
Chu, Tian-Shu; Han, Ke-Li; Varandas, António J. C.We report a dynamics study of the reaction N(2D) + H2 (v=0, j=0−5) → NH + H using the time-dependent quantum wave packet method and a recently reported single-sheeted double many-body expansion potential energy surface for NH2(12A‘‘) which has been modeled from accurate ab initio multireference configuration-interaction calculations. The calculated probabilities for (v=0, j=0−5) are shown to display resonance s...
A novel accurate representation of a double-valued potential energy surface by ...
Varandas, António J. C.; Alijah, Alexander; Cernei, MihailStandard single-valued double many-body expansion (DMBE) theory has been extended to allow an accurate representation of a double-valued potential energy surface. With this new theory, the degeneracy of the two sheets along the conical intersection line can be guaranteed by construction. The method has been applied to the lowest triplet state of H3+ (a3E') for which the lowest vibrational levels have also been ...
Dynamics Study of the O + HO2 Reaction Using Two DMBE Potential Energy Surfaces...
Silveira, Dora M.; Caridade, Pedro J. S. B.; Varandas, António J. C.We investigate the effect of vibrational excitation on the dynamics and kinetics of the atmospheric reaction O(3P) + HO2 → OH + O2 using two double many-body expansion potential energy surfaces previously reported. The results show that such an effect is relatively minor even considering HO2 with contents of vibrational excitation close to the H + O2 dissociation asymptote. It should therefore not bear drastic ...
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