Potential energy surface for H2O(3A″) from accurate <i>ab initio</i> data with inclusion of long-range interactions

Brandão, João; Mogo, César; Silva, Bruno C. da

doi:10.1063/1.1802434

Cited by 35 publications

(53 citation statements)

References 29 publications

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“…18 This demand is motivating work on ab initio methods capable of yielding the desired accuracy 4,5,[19][20][21] and the search for new methodological approaches. [22][23][24][25][26][27] Interest also continues in methods for deducing accurate potential energy functions directly from observed vibrational spectra. [28][29][30] The best available potential energy curves are also useful in the modeling of "universal" potential energy functions.…”

Section: Introductionmentioning

confidence: 99%

Accurate ab initio potential energy curve of F2. III. The vibration rotation spectrum

Bytautas

Matsunaga

Nagata

et al. 2007

The Journal of Chemical Physics

134

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An analytical expression is found for the accurate ab initiopotential energy curve of the fluorine molecule that has been determined in the preceding two papers. With it, the vibrational and rotational energy levels of F2 are calculated using the discrete variable representation. The comparison of this theoretical spectrum with the experimental spectrum, which had been measured earlier using high-resolution electronic spectroscopy, yields a mean absolute deviation of about 5cm−1 over the 22 levels. The dissociation energy with respect to the lowest vibrational energy is calculated within 30cm−1 of the experimental value of 12953±8cm−1. The reported agreement of the theoretical spectrum and dissociation energy with experiment is contingent upon the inclusion of the effects of core-generated electron correlation,spin-orbit coupling, and scalar relativity. The Dunham analysis [Phys. Rev.41, 721 (1932)] of the spectrum is found to be very accurate. New values are given for the spectroscopic constants. KeywordsAb initio calculations, Dissociation energies, Polynomials, Dissociation, Electron correlation calculations Disciplines Chemistry CommentsThe following article appeared in Journal of Chemical Physics 127 (2007) An analytical expression is found for the accurate ab initio potential energy curve of the fluorine molecule that has been determined in the preceding two papers. With it, the vibrational and rotational energy levels of F 2 are calculated using the discrete variable representation. The comparison of this theoretical spectrum with the experimental spectrum, which had been measured earlier using high-resolution electronic spectroscopy, yields a mean absolute deviation of about 5 cm −1 over the 22 levels. The dissociation energy with respect to the lowest vibrational energy is calculated within 30 cm −1 of the experimental value of 12 953± 8 cm −1 . The reported agreement of the theoretical spectrum and dissociation energy with experiment is contingent upon the inclusion of the effects of core-generated electron correlation, spin-orbit coupling, and scalar relativity. The Dunham analysis ͓Phys. Rev. 41, 721 ͑1932͔͒ of the spectrum is found to be very accurate. New values are given for the spectroscopic constants.

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Section: Introductionmentioning

confidence: 99%

Accurate ab initio potential energy curve of F2. III. The vibration rotation spectrum

Bytautas

Matsunaga

Nagata

et al. 2007

The Journal of Chemical Physics

134

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“…Then, the present reaction rates were obtained by averaging the two states so that [20]. We used the GLDP1 global PES for OH 2 ( 3 A ) developed by Rogers et al [21] and the BMS1 global PES for OH 2 ( 3 A ) developed by Brandão et al [22], which was an extension of a PES developed by Rogers et al [21]. Finally, we used WDSE-RB global PES for OH 3 developed by Rashed and Brown [23], which was an extension of the Schatz-Elgersma analytical fit to the Walsh-Dunning PES [24].…”

Section: Resultsmentioning

confidence: 99%

Effect of thermal nonequilibrium on reactions in hydrogen combustion

2016

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The presence of shocks in scramjet internal flows introduces nonequilibrium of internal energy modes of the molecules. Here, the effect of vibrational nonequilibrium on key reactions of hydrogen-air combustion is studied. A quasi-classical trajectory (QCT) approach is used to derive reaction probability for nonequilibrium conditions using ab initio-derived potential energy surfaces. The reaction rates under nonequilibrium are studied using a two-temperature description, where the vibrational modes are assumed to be distributed according to a Boltzmann distribution at a characteristic vibrational temperature, in addition to a translational temperature describing the translational and rotational population distribution. At scramjet-relevant conditions, it is found that the nonequilibrium reaction rate depends not only on the level of vibrational excitation, but also on the reactants involved. Conventional two-temperature models for reaction rates, often derived using empirical means, were found to be inaccurate under these conditions, and modified parameters are proposed based on the QCT calculations. It is also found that models that include details of the reaction process through dissociation energy, for instance, provide a better description of nonequilibrium effects.

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“…We have studied theoretically theses reactions in the past 13,19,[23][24][25] , and here, using some of our previous trajectories calculations results, we can show that two different types of dynamical behaviour can be exemplified by these two reactions.…”

Section: A Reaction Dynamicsmentioning

confidence: 99%

“…In addition, this Σ PES correlates with the product OH diatomic in its first excited state, OH( 2 Σ) and does not contribute to the title reaction at the energies of chemical practical interest. To illustrate the main differences between these reactions, here we use two of our published a PESs 23,24 for singlet and triplet state of this system as examples. The Figure 3 is a three dimensional view of an O( …”

Section: The Detailed Interaction Between O Atom and H 2 Moleculementioning

confidence: 99%

Using the Reactions O+H<sub>2</sub> → OH+H to Explore the Importance of the Atomic Quantum States on Chemical Kinetics and Reaction Dynamics

Brandão¹,

Wang²,

Rio³

2015

ujc

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The O + H 2 reaction is a particular example to alert the importance of a clear definition of the quantum state of an atom when referring to a chemical reaction. In its ground state, O ( 3 P), the oxygen atom reacts with H 2 through an energy barrier with small rate constant. In contrast, when the oxygen atom is in its first excited state, O ( 1 D), the reaction O + H 2 occurs without energy barrier and the rate constant is seven orders of magnitude higher. The dynamic behaviour of this reaction depends also on the quantum state of the oxygen atom.

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Potential energy surface for H2O(3A″) from accurate ab initio data with inclusion of long-range interactions

Cited by 35 publications

References 29 publications

Accurate ab initio potential energy curve of F2. III. The vibration rotation spectrum

Accurate ab initio potential energy curve of F2. III. The vibration rotation spectrum

Effect of thermal nonequilibrium on reactions in hydrogen combustion

Using the Reactions O+H<sub>2</sub> → OH+H to Explore the Importance of the Atomic Quantum States on Chemical Kinetics and Reaction Dynamics

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