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Copyright of Investigación y Ciencia de la Universidad Autónoma de Aguascalientes is the property of Universidad Autonoma de Aguascalientes, Direccion General de Investigacion y Posgrado and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista del Centro de Investigación. Universidad La Salle is the property of Universidad La Salle and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reduction kinetics of allura red dye (E-129, C.I. 16035) by sodium bisulfite at level B3LYP/6-31G(d) in aqueous phase was determined. This was done to evaluate a plausible mechanistic path for the reduction reaction of this important azo dye used in the food industry. The predicted rate constants (kSulf) for the sulfonation step were in good agreement with respect to experimental rate constants reported for some dyes of chemical structure similar to Allura red. On the B3LYP potential energy surface, were located five stationary points corresponding to reactants, transition states and products. The transition states for the first and second step of the reduction reaction are presented for the first time and characterized by calculations of intrinsic reaction coordinate and vibrational frequencies. The activation thermodynamic parameters indicated than the reaction was stable, endothermic and non-spontaneous. [ABSTRACT FROM AUTHOR]

Copyright of Revista Cubana de Ciencias Informáticas is the property of Universidad de las Ciencias Informaticas (UCI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using the classical trajectory method, the dynamics of mole- cular recombination of Nitrogen atoms from a Tungsten (100) surface is studied. The potential energy surface is an extended version of the periodic London-Eyring-Polanyi-Sato potential, recently developed. The dynamics is explored in a wide range of projectile energies. We focus our attention on the Eley-Rideal recombination cross section. The influence of adsorved atoms is only significant inside the occupied cell. [ABSTRACT FROM AUTHOR]

Using the classical trajectory method, the dynamics of molecular recombination of Nitrogen atoms from a Tungsten (100) surface is studied. We focus our attention on the Eley-Rideal (ER) recombination mechanism. The potential energy surface is an extended version of the periodic London-Eyring-Polanyi-Sato potential, recently developed. The dynamics is explored in a wide range of projectile energies, the main objective being to compare the behavior of the probability for ER recombination and hot-atoms (HA) formation. [ABSTRACT FROM AUTHOR]

A Potential Energy Surface for the SO3 in the lowest triplet electronic state, using the double many body expansion (DMBE) method is presented. Previous functions reported for diatomic and triatomic fragments, obtained by the same method, as well as four-body electrostatic energy term considering the long range interactions were employed. The so obtained PES reproduces the asymptotic limits and predicts some stable configurations previously reported from molecular orbital ab-initio calculations (as the global minimum in D3h symmetry) and experimental results. Such a sixdimensional function was characterized describing the properties of stationary points and some of the reaction mechanism taking place on it. The reaction S(³P)+O3(<¹A1) was studied using the PES and the quasiclassic trajectories method, being formation of SO+O2 the favored process. The excitation function shows a capture type behavior for the low energies. Details for reaction mechanism and rate constant are also presented [ABSTRACT FROM AUTHOR]

The reactive and vibrational relaxation processes, occurring in collisions of vibrational excited O2 and OH, are investigated using the quasi-classical trajectory method and the realistic double many-body expansion (DMBE-I) potential energy surface for ground-state HO3. Calculations have covered a wide range of combinations of vibrational excited states of involved molecules to warrant the definition of models with correct analytical descriptions of the specific thermal rate coefficients for all interesting processes. It is also shown that the vibrational relaxation of colliding molecules is less important than the reactive processes leading to formation of "odd-oxygen" (and hence ozone). [ABSTRACT FROM AUTHOR]

We report a theoretical study of the title four-atom reaction for a wide range of translational energies, considering the reactants in the ground vibrational state and also in some vibrationally excited levels of the HS radical. All calculations have employed the quasiclassical trajectories method (QCT) and a recently reported double many-body expansion potential energy surface for the ground electronic state of HSO2 . Cross section, specific thermal rate coefficients and vibrationally averaged thermal rate coefficient are reported. To account the leak of zero point energies a QCT intermediate vibrational energy (IVEQMT) criteria is used. [ABSTRACT FROM AUTHOR]

The application of the Quasi-Classical Trajectory Method in the study of the vibrational predissociation of the NeBr2 (X, v = 1) molecular system is presented. The full dimensionality of the system was included in the model and the total angular momentum was taken to be zero (J = 0). The successive application of various numerical interpolation methods was used for both the reproduction and derivative computation of the Potential Energy Surface [Prosmiti et al. J. Chenu Phys. 117, 10019 (2002)]. The quantum distribution corresponding to the state under study was computed by using a diabatic separation of the Jacobi variables r and (R, θ). Classical initial conditions were calculated to reproduce this statistical distribution. Practical limitations affected the total number of trajectories to be propagated. However, we show how the main dynamical features of the process can be understood from a representative set of these and a complementary analysis of both the PES and its derivatives. Several limitations of the methodology are discussed and so are some of their possible solutions. [ABSTRACT FROM AUTHOR]

The phase space structure of a generic Hamiltonian model describing the vibrational dynamics of the molecular complexes GrBr2(X) (Gr = He, Ne, Ar) is studied, by constructing the Poincaré surfaces of section and considering results of the Canonical Perturbation Theory. According to our results, we can assure that all the systems studied here exhibit near-integrable behavior, and that the collocation coefficients contain qualitatively important information about the Hamiltonian perturbation strength. The cited perturbation strength, is found to be strongly dependent on the considered isomer (linear or T) so as the rare gas involved. Finally, an undesired feature of the potential energy surface reported in [27] for the HeBr2 molecule is also briefly commented. [ABSTRACT FROM AUTHOR]

Copyright of Revista Luna Azul is the property of Universidad de Caldas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A detailed theoretical study of the Potential Energy Surface (PES), corresponding to the reaction of thermal decomposition of the furan, was carried out. Different theory levels [PM3, AM1, HF/6-31G(d), BLYP/6-31G(d) and B3LYP/6-31G(d)] were evaluated. A local modification to the G2(B3LYP/MP2/ CC) methodology was used to characterize the located stationary points. Two reaction mechanisms were found: the formation of propyne (I) and/or propadiene (II), with CO elimination in both cases. Both mechanisms are very competitive; from the thermodynamic point of view the mechanism I is favored for 7,53 kJmol-1 (1,8 kcalmol-1). Also, a pathway I is kinetically favored, it would involve a two-step mechanism while II has a step more . The results are in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Ingeniería Biomédica is the property of Sociedad Mexicana de Ingenieria Biomedica, A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)