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On the Use of Different Potential Energy Functions in Rare-Gas Cluster Optimiza...
Marques, J. M. C.; Pereira, F. B.; Leitão, T.We study the effect of the potential energy function on the global minimum structures of argon clusters arising in the optimization performed by genetic algorithms (GAs). We propose a robust and efficient GA which allows for the calculation of all of the putative global minima of ArN (N = 3−78) clusters modeled with four different potentials. Both energetic and structural properties of such minima are compared ...
Kinetics and dynamics of O + OClO reaction in a modified many-body expansion po...
Teixeira, O. B. M.; Marques, J. M. C.; Varandas, A. J. C.The ClO3 many-body expansion potential energy surface of Farantos and Murrell (Int J Quantum Chem 1978, 14, 659) has been modified along the minimum energy path for the reaction O + OClO rarr ClO + O2 such as to conform with the available kinetics data. The dynamics of the title reaction is also studied for temperatures of relevance in stratospheric chemistry. Two mechanisms for ClO + O2 formation are identifie...
Trajectory Dynamics Study of Collision-Induced Dissociation of the Ar + CH4 Rea...
Marques, J. M. C.; Martínez-Núñez, E.; Vázquez, S. A.We investigate the role of vibrational energy excitation of methane and two deuterated species (CD4 and CH2D2) in the collision-induced dissociation (CID) process with argon at hyperthermal energies. The quasi-classical trajectory method has been applied, and the reactive Ar + CH4 system has been modeled by using a modified version of the CH4 potential energy surface of Duchovic et al. (J. Phys. Chem. 1984, 88,...
Trajectory Dynamics Study of the Ar + CH4 Dissociation Reaction at High Tempera...
Marques, J. M. C.; Martínez-Núñez, E.; Fernández-Ramos, A.; Vázquez, S. A.Large-scale classical trajectory calculations have been performed to study the reaction Ar + CH4 → CH3 + H + Ar in the temperature range 2500 ≤ T/K ≤ 4500. The potential energy surface used for ArCH4 is the sum of the nonbonding pairwise potentials of Hase and collaborators (J. Chem. Phys. 2001, 114, 535) that models the intermolecular interaction and the CH4 intramolecular potential of Duchovic et al. (J. Phys...
Li + Li2 Dissociation Reaction Using the Self-Consistent Potential and Trajecto...
Marques, J. M. C.; Voronin, A. I.; Varandas, A. J. C.Self-consistent potential and trajectory surface hopping methods have been applied to study the Li + Li2 dissociation reaction. Both methods fall into the classical trajectory methodology, with batches of 5000 trajectories being run over the translational energy range 25 ≤ Etr ≤ 100 kcal mol-1 keeping the internal state of Li2 fixed at (v = 0, j = 10). The effect of vibrational excitation has also been studied ...
Mode Specificity Study in Unimolecular Dissociation of Nonrotating H2O, DHO, an...
Llanio-Trujillo, J. L.; Marques, J. M. C.; Varandas, A. J. C.Classical trajectory calculations for the unimolecular dissociation of nonrotating H2O, DHO, and MuHO are reported for different distributions of energy among the three vibrational normal modes. The calculations employ a realistic energy-switching potential energy surface for the electronic ground state of the water molecule. It is found that the unimolecular decay rates vary with the vibrational mode of the wa...
Comparative trajectory surface hopping study for the Li+Li2(X1g+), Na+Li2(X1g+)...
Marques, J. M. C.; Voronin, A. I.; Varandas, A. J. C.Trajectory surface hopping calculations are presented for the Li+Li2 (X1g+), Na+Li2 (X1g+) and Li+Na2 (X1g+) dissociation reactions using realistic potential energy surfaces for the lowest doublet states of Li3, NaLi2, and LiNa2. The calculations were carried out over the range of translational energies Etr=11.5–80.0 kcal mol-1 and vibrational quantum numbers v=0, 10, and 20 for Li2 (X1g+) and Na2 (X1g+). A com...
Trajectory Surface Hopping Study of the Li + Li2(X1Σg+) Dissociation Reaction
Voronin, A. I.; Marques, J. M. C.; Varandas, A. J. C.Trajectory surface hopping calculations are reported for the Li + Li2(X1Σg+) dissociation reaction over the range of translational energies 13 ≤ Etr/kcal mol-1 ≤ 80. Both potential energy surfaces for ground doublet Li3, which have been modeled from the double many-body expansion method (DMBE III), have been employed in the dynamics calculations. For the initial internal state (v = 0, j = 10), the behavior of t...
Classical Trajectory Study of Mode Specificity and Rotational Effects in Unimol...
Marques, J. M. C.; Varandas, A. J. C.Trajectory calculations are presented for the unimolecular dissociation of HO2. The study covers internal energies in the range 58.311 ≤ Etot/kcal mol-1 ≤ 59.432, just above the H + O2 threshold, and Etot = 76.412 kcal mol-1 for which the O + OH channel is also open. The HO2 single-valued double many-body expansion potential energy surface has been employed in all calculations. Due to strong coupling among the ...
Dynamics Study of the H + ArO2 Multichannel Reaction
Marques, J. M. C.; Wang, W.; Pais, A. A. C. C.; Varandas, A. J. C.Trajectory calculations have been carried out for the title reaction over the range of translational energies 0.25 ≤ Etr/kcal mol-1 ≤ 131.4. We present reactive cross sections for formation of stable HO2 for translational energies up to 8.0 kcal mol-1, while for O2 formation the reported cross sections extend over the whole range of translational energies. The former cross sections are shown to decrease with in...
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