Trajectory binning scheme and non-active treatment of zero-point energy leakage in quasi-classical dynamics

By expressing an unknown state in terms of a complete set, a simple scheme for approximate quantization of the continuous vibrational-rotational energy distributions that are obtained from quasi-classical trajectory calculations is suggested. The problem of zero-point energy leakage is also revisited, and the new method tested on the prototype O + OH and H + D2 reactions.http://www.sciencedirect.com/science/article/B6TFN-4NCJCX1-3/1/cba1ca88eec1685b1502de957a8cc17

Ab initio potentials: From CBS extrapolation to globalness to riddles in the chemistry of small carbon clusters

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Classe de Ciências

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HN2(2A‘) Electronic Manifold. I. A Global ab Initio Study of First Two States

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 NHN loci of conical intersections is also reported, jointly with a discussion of the topological features associated to a newly reported 22A‘/32A‘ crossing seam

Approximate Quantum Mechanical Cross Sections and Rate Constants for the H + O3 Atmospheric Reaction Using Novel Elastic Optimum Angle Adiabatic Approaches

Three-dimensional quantum dynamics computations of cross sections and rate constants for the atmospheric reaction H + O3 → O2 + OH are presented. Using a novel elastic optimum angle adiabatic approach published in a previous paper (Varandas, A. J. C.; Szichman, H. Chem. Phys. Lett. 1998, 295, 113), the calculated cross sections cover the range of translational energies 0.035 ≤ Etr/eV ≤ 0.300. Applications of the new approach using both single-path and multiple-path schemes are reported. The results are compared with available classical trajectory and infinite-order-sudden-approximation results. It may be concluded that the calculations obtained from the single-path model give an improved agreement with respect to the sudden ones when compared with the classical trajectory results. In turn, the quantum elastic optimum angle adiabatic multiple-path results show excellent agreement with the same classical results

Ro-Vibrational States of Triplet H2D

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

Test studies on the potential energy surface and rate constant for the OH+O3 atmospheric reaction

We report a single-valued potential energy surface for HO4(2A) from the double many-body expansion method. All n-body (n=2-4) energy terms are taken from published studies on the relevant fragments, with a five-body energy term of Gaussian form added to mimic the experimental activation energy for the OH(v=0)+O3 reaction. A detailed dynamics study of this reaction is also reported using classical trajectories. Good agreement with existing experimental data is obtained.http://www.sciencedirect.com/science/article/B6TFN-41WBCGK-M/1/f846c63bce20f7a4c43e3cdd2338c85