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Potential Energy Surface for Ground-State H2S via Scaling of the External Corre...
Song, Y. Z.; Caridade, P. J. S. B.; Varandas, A. J. C.A global double many-body expansion potential energy surface is reported for the electronic ground state of H2S by fitting accurate ab initio energies calculated at the multireference configuration interaction level with the aug-cc-pVQZ basis set, after slightly correcting semiempirically the dynamical correlation by the double many-body expansion-scaled external correlation method. The function so obtained has...
A Theoretical Study of Rate Coefficients for the O + NO Vibrational Relaxation
Caridade, P. J. S. B.; Mota, V. C.; Mohallem, J. R.; Varandas, A. J. C.Quasi-classical trajectories have been integrated to study the vibrational relaxation of the O + NO(v) process as a function of the initial vibrational quantum number for T = 298 K, 1500 K, and 3000 K. Two reliable potential energy surfaces have been employed for the A‘ and A‘ ‘ doublet states of NO2. The calculated vibrational relaxation rate constants show a nearly v-independent behavior at room temperature a...
Recalibrated Double Many-Body Expansion Potential Energy Surface and Dynamics C...
Caridade, P. J. S. B.; Poveda, L. A.; Rodrigues, S. P. J.; Varandas, A. J. C.A single-sheeted double many-body expansion potential energy surface is reported for the lowest doublet state of HN2 by fitting additional multireference configuration interaction energies in the N···NH channel. A stratified analysis of the root-mean-squared error indicates an accuracy superior to that achieved for the previously reported form. Detailed dynamical tests are also performed for the N + NH reaction...
Unimolecular and Bimolecular Calculations for HN2
Caridade, P. J. S. B.; Rodrigues, S. P. J.; Sousa, F.; Varandas, A. J. C.Using a recently reported double many-body expansion potential energy surface, quasi-classical, statistical mechanics, and quantum resonance calculations have been performed for the HN2 system by focusing on the determination of bimolecular (N + NH and H + N2) and unimolecular (decomposition of HN2) rate constants as well as the relevant equilibrium constants. ; http://dx.doi.org/10.1021/jp045102g
Nascent versus “Steady-State” Rovibrational Distributions in the Products of th...
Caridade, P. J. S. B.; Llanio-Trujillo, J. L.; Varandas, A. J. C.We report a trajectory simulation study of the O2(v‘,j‘) + O2(v‘‘,j‘‘) collisional process at a translational temperature of 1500 K with a view to compare the initial and final rovibrational distributions of the colliding species. As initial rotational and vibrational micropopulations we assume those calculated for the products of the forward title reaction. Rotational relaxation is found to occur to a larger e...
Dynamics Study of the OH + O2 Branching Atmospheric Reaction. 4. Influence of V...
Garrido, J. D.; Caridade, P. J. S. B.; Varandas, A. J. C.The vibrational relaxation processes occurring during collisions of vibrationally excited O2 and OH are investigated using the quasiclassical trajectory method and a realistic double many-body expansion (DMBE I) potential energy surface for ground-state HO3. A salient feature is the observation of multiquanta deactivation processes for such high internal energies. It is also shown that the vibrational relaxatio...
Dynamics Study of the OH + O2 Branching Atmospheric Reaction. 2. Influence of R...
Caridade, P. J. S. B.; Zhang, L.; Garrido, J. D.; Varandas, A. J. C.The effect of reactants vibrational and rotational excitation on products (HO2 + O and O3 + H) formation is investigated for the title reaction by using the quasiclassical trajectory method and the realistic double many-body expansion (DMBE) potential energy surface for ground-state HO3. It is shown that it can be a potential source of ozone in the upper atmosphere. ; http://dx.doi.org/10.1021/jp004308o
Dynamics Study of the OH + O2 Branching Atmospheric Reaction. 3. Dissociation i...
Caridade, P. J. S. B.; Betancourt, M.; Garrido, J. D.; Varandas, A. J. C.We discuss the dissociation of the OH radical in the title molecular collisions when both species are vibrationally excited. An analysis of the O2 dissociation is also reported. All calculations employed the quasiclassical trajectory method and a realistic double many-body expansion (DMBE) potential energy surface for ground-state HO3. The results are compared with those referring to formation of HO2 and O3 und...
Is there a barrier for the C2v insertion reaction in O(1D)+H2? A test dynamics ...
Varandas, A. J. C.; Voronin, A. I.; Caridade, P. J. S. B.; Riganelli, A.We have calculated cross-sections and rate constants for the title reaction by using the quasiclassical trajectory method and a recently reported two-valued energy-switching potential energy surface for the water molecule. By varying the amplitude and rate of decay of a local Gaussian term which controls the appearance of a barrier along the C2v minimum energy profile, an attempt has been made to answer the tit...
Dynamics Study of the HO(v‘=0) + O2(v‘ ‘) Branching Atmospheric Reaction. 1. Fo...
Garrido, J. D.; Caridade, P. J. S. B.; Varandas, A. J. C.We report a theoretical study of the title four-atom atmospheric reaction for a range of translational energies 0.1 ≤ Etr/kcal mol-1 ≤ 40 and the range 13 ≤ v‘ ‘ ≤ 27 of vibrational quantum numbers of the oxygen molecule. All calculations have employed the quasiclassical trajectory method, and a realistic potential energy surface obtained by using the double many-body expansion (DMBE) method for ground-state HO...
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