Theoretical investigation of the dissociation dynamics of vibrationally excited vinyl bromide on an <i>ab initio</i> potential-energy surface obtained using modified novelty sampling and feedforward neural networks. II. Numerical application of the method

Malshe, M.; Raff, Lionel M.; Rockley, Mark G.; Hagan, Martin T.; Agrawal, Paras M.; Komanduri, R.

doi:10.1063/1.2768948

Cited by 57 publications

(54 citation statements)

References 24 publications

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“…The complex molecular dissociation of six-atom vinyl bromide (CH 2 CHBr) includes at least four reaction channels and thus becomes an extremely challenging task when the PES is developed. Malshe et al [55] have demonstrated a typical study of the vinyl bromide system, in which nearly 72,000 data points were sampled, and a two-layer NN was employed to fit the PES. This approach has been further employed to investigate the reaction dynamics of SiO 2 [56], HONO [57], HOOH [58], BeH 3 [59], and O 3 [60] systems.…”

Section: Neural Network (Nn) Fittingmentioning

confidence: 99%

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Molecular dynamics investigations of chlorine peroxide dissociation on a neural network ab initio potential energy surface

Dinh

et al. 2012

Theor Chem Acc

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Molecular dissociation of chlorine peroxide (ClOOCl), which consists of two elementary dissociation channels (of Cl-O and O-O), is investigated using molecular dynamics simulations on a neural network-fitted potential energy surface constructed by MP2 calculations with the 6-311G(d,p) basis set. When relaxed scans of the surface are executed, we observe that Cl-O dissociation is extremely reactive with a low barrier height of 0.1928 eV (18.602 kJ/mol), while O-O bond scission is less reactive (0.7164 eV or 69.122 kJ/mol). By utilizing the ''novelty sampling'' method, 35,006 data points in the ClOOCl configuration hyperspace are collected, and a 40-neuron feed-forward neural network is employed to fit approximately 90% of the data to produce an analytic potential energy function. The mean absolute error and root mean squared error of this fit are reported as 0.0078 eV (0.753 kJ/ mol) and 0.0137 eV (1.322 kJ/mol), respectively. Finally, quasi-classical molecular dynamics is executed at various levels of internal energy (from 0.8 to 1.3 eV) to examine the bond ruptures. The two first-order rate coefficients are computed statistically, and the results range from 5.20 to 22.67 ps -1 for Cl-O dissociation and 3.72-8.35 ps -1 for O-O dissociation. Rice-Ramsperger-Kassel theory is utilized to classically correlate internal energies to rate coefficients in both cases, and the plots exhibit very good linearity, thus can be employed to predict rate coefficients at other internal energy levels with good reliability.

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Section: Neural Network (Nn) Fittingmentioning

confidence: 99%

“…The PES construction requires an efficient sampling procedure [55][56][57]65] to sufficiently select data points from the multi-dimensional hyperspace. A particular construction of the NN PES perhaps requires more configurations to be selected than the other PES fitting methods.…”

Section: Novelty Sampling Of Configurations In Multi-dimensional Hypementioning

confidence: 99%

Molecular dynamics investigations of chlorine peroxide dissociation on a neural network ab initio potential energy surface

Dinh

et al. 2012

Theor Chem Acc

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“…Anharmonic fundamental vibrational frequencies of vinyl fluoride, 68 vinyl chloride, 69 and vinyl bromide [70][71][72] have been extensively studied theoretically. For C 2 H 3 F, C 2 H 3 Cl, and C 2 H 3 Br, Demaison and co-workers 70 calculated the quartic force fields by using second-order Møller-Plesset perturbation theory with the cc-pVTZ basis set.…”

Section: B Vinyl Fluoride Vinyl Chloride and Vinyl Bromidementioning

confidence: 99%

Solving the eigenvalue equations of correlated vibrational structure methods: Preconditioning and targeting strategies

Győrffy

Seidler

Christiansen

2009

The Journal of Chemical Physics

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Various preconditioners and eigenvector targeting strategies in combination with the Davidson and Olsen methods are presented for solving eigenvalue equations encountered in vibrational configuration interaction, its response generalization, and vibrational coupled cluster response theory. The targeting methods allow significant flexibility and robustness in computing selected vibrational states, which are particularly important in the often occurring but nontrivial cases of near degeneracies. We have investigated the effect of a mode-excitation level-based generally applicable preconditioning scheme aiming to improve the robustness of the more standard diagonal preconditioning method. Although increasing convergence rates may be achieved in general through a hierarchy of these preconditioners, the strategy is not always beneficial in terms of CPU time. Features of the methods are demonstrated in calculations of the overtone vibrational states of formaldehyde and the fundamental states of vinyl fluoride, vinyl chloride, vinyl bromide, and naphthalene.

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“…To do this, one calculates electronic energies at a large number of points and fits a functional form to them. [28][29][30][31][32][33][34][35][36] Methods for the calculation of energy levels and wave functions have evolved with the ability of quantum chemists to calculate reasonably accurate potentials. In this article, I shall focus on ideas for using product basis sets.…”

Section: Introductionmentioning

confidence: 99%

Two new methods for computing vibrational energy levels

Carrington

2015

Can. J. Chem.

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I review two new ideas for coping with the size of large product basis sets and large product grids when one computes vibrational energy levels. The first is based on a tensor reduction scheme. It exploits advantages of a sum-of-products potential.The key idea is to use a basis each of whose function is a sum of optimized products and to compress the number of terms in each basis function. When the potential does not have the sum-of-products form, it is usually necessary to use quadrature. The second idea uses a nondirect product grid that has structure and is therefore compatible with efficient matrix-vector products.Résumé : Cet article décrit deux nouvelles approches permettant l'utilisation d'une grande base de produits afin de calculer des niveaux vibrationnels. La première est fondée sur la réduction des tenseurs. Elle exploite les avantages d'un potentiel ayant la forme d'une somme de produits. L'idée clef est d'utiliser une base dont chacune des fonctions est une somme de produits optimisés et de comprimer le nombre de termes dans chaque fonction de la base. Si le potentiel n'est pas une somme de produits, il faut utiliser une quadrature. La seconde approche consiste à utiliser une grille qui n'est pas un produit direct mais qui a assez de structure pour faciliter le calcul de produits matrice-vecteur.Mots-clés : théorie, spectroscopie rotationnelle-vibrationnelle, méthodes itératives, algorithme de Lanczos.

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Theoretical investigation of the dissociation dynamics of vibrationally excited vinyl bromide on an ab initio potential-energy surface obtained using modified novelty sampling and feedforward neural networks. II. Numerical application of the method

Cited by 57 publications

References 24 publications

Molecular dynamics investigations of chlorine peroxide dissociation on a neural network ab initio potential energy surface

Molecular dynamics investigations of chlorine peroxide dissociation on a neural network ab initio potential energy surface

Solving the eigenvalue equations of correlated vibrational structure methods: Preconditioning and targeting strategies

Two new methods for computing vibrational energy levels

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