Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Martı́nez-Núñez, Emilio; Vázquez, Saulo A.; Varandas, A. J. C.

doi:10.1039/b107511j

Cited by 19 publications

(19 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…71 and 72͒ with both double-zeta and triple-zeta Pople [73][74][75][76][77][78] and Dunning basis sets. [79][80][81][82][83][84][85][86][87][88][89][90][91][92] For comparative purposes we used a MEP generated by performing UB3LYP/ augЈ-cc-pVTZ geometry optimizations for a series of constrained C-C distances starting from 1.38 Å, corresponding to the optimized triplet acetaldehyde geometry, and increasing in 0.1 Å steps. The energy profiles along this path were examined as a function of basis-set size and ab initio method.…”

Section: A Potential-energy Surface Constructionmentioning

confidence: 99%

A classical trajectory study of the photodissociation of T1 acetaldehyde: The transition from impulsive to statistical dynamics

Thompson

Crittenden

Kable

et al. 2006

The Journal of Chemical Physics

View full text Add to dashboard Cite

Previous experimental and theoretical studies of the radical dissociation channel of T(1) acetaldehyde show conflicting behavior in the HCO and CH(3) product distributions. To resolve these conflicts, a full-dimensional potential-energy surface for the dissociation of CH(3)CHO into HCO and CH(3) fragments over the barrier on the T(1) surface is developed based on RO-CCSD(T)/cc-pVTZ(DZ) ab initio calculations. 20,000 classical trajectories are calculated on this surface at each of five initial excess energies, spanning the excitation energies used in previous experimental studies, and translational, vibrational, and rotational distributions of the radical products are determined. For excess energies near the dissociation threshold, both the HCO and CH(3) products are vibrationally cold; there is a small amount of HCO rotational excitation and little CH(3) rotational excitation, and the reaction energy is partitioned dominantly (>90% at threshold) into relative translational motion. Close to threshold the HCO and CH(3) rotational distributions are symmetrically shaped, resembling a Gaussian function, in agreement with observed experimental HCO rotational distributions. As the excess energy increases the calculated HCO and CH(3) rotational distributions are observed to change from a Gaussian shape at threshold to one more resembling a Boltzmann distribution, a behavior also seen by various experimental groups. Thus the distribution of energy in these rotational degrees of freedom is observed to change from nonstatistical to apparently statistical, as excess energy increases. As the energy above threshold increases all the internal and external degrees of freedom are observed to gain population at a similar rate, broadly consistent with equipartitioning of the available energy at the transition state. These observations generally support the practice of separating the reaction dynamics into two reservoirs: an impulsive reservoir, fed by the exit channel dynamics, and a statistical reservoir, supported by the random distribution of excess energy above the barrier. The HCO rotation, however, is favored by approximately a factor of 3 over the statistical prediction. Thus, at sufficiently high excess energies, although the HCO rotational distribution may be considered statistical, the partitioning of energy into HCO rotation is not.

show abstract

Section: A Potential-energy Surface Constructionmentioning

confidence: 99%

A classical trajectory study of the photodissociation of T1 acetaldehyde: The transition from impulsive to statistical dynamics

Thompson

Crittenden

Kable

et al. 2006

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…Using the DMBE PES, Martínez-Núñez et al 19 have performed classical dynamics calculations for the lowest energy unimolecular reaction channels of HSO. Using the DMBE PES, Martínez-Núñez et al 19 have performed classical dynamics calculations for the lowest energy unimolecular reaction channels of HSO.…”

Section: Introductionmentioning

confidence: 99%

Quantum dynamics of the S+OH→SO+H reaction

Jorfi

Honvault

2010

The Journal of Chemical Physics

View full text Add to dashboard Cite

First accurate quantum mechanical scattering calculations have been carried out for the S((3)P)+OH(X (2)Π)→SO(X (3)Σ(-))+H((2)S) reaction using a recent ab initio potential energy surface for the ground electronic state, X (2)A("), of HSO. Total and state-to-state reaction probabilities for a total angular momentum J=0 have been determined for collision energies up to 0.5 eV. A rate constant has been calculated by means of the J-shifting approach in the 10-400 K temperature range. Vibrational and rotational product distributions show no specific behavior and are consistent with a mixture of direct and indirect reaction mechanisms.

show abstract

“…In any case, the known experimental data for HSO will serve as a barometer for the quality of the CcCR computations utilized in this work to predict the rotational constants and vibrational frequencies for HSS and HOS. Finally, HSO isomerizes to HOS preferentially when compared to hydride dissociation (Martinez-Nunez et al 2002), and is known to be 4.2 kcal mol −1 lower in energy than HOS (Wilson & Dunning 2004). As a result, if HSO has any abundance in the ISM, HOS likely will, as well, and its spectroscopic values can be refined beyond those available in the current literature (Denis 2009;Ovsyannikov et al 2013).…”

Section: Introductionmentioning

confidence: 99%

On the Detectability of the HSS, HSO, and HOS Radicals in the Interstellar Medium

Fortenberry

Francisco

2017

ApJ

View full text Add to dashboard Cite

HSS has yet to be observed in the gas phase in the interstellar medium (ISM). HSS has been observed in cometary material and in high abundance. However, its agglomeration to such bodies or dispersal from them has not been observed. Similarly, HSO and HOS have not been observed in the ISM, either, even though models support their formation from reactions of known sulfur monoxide and hydrogen molecules, among other pathways. Consequently, this work provides high-level, quantum chemical rovibrational spectroscopic constants and vibrational frequencies in order to assist in interstellar searches for these radical molecules. Furthermore, the HSO −HOS isomerization energy is determined to be 3.63 kcal mol −1 , in line with previous work, and the dipole moment of HOS is 36% larger at 3.87 D than HSO, making the less stable isomer more rotationally intense. Finally, the S−S bond strength in HSS is shown to be relatively weak at 30% of the typical disulfide bond energy. Consequently, HSS may degrade into SH and sulfur atoms, making any ISM abundance of HSS likely fairly low, as recent interstellar surveys have observed.

show abstract

Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Cited by 19 publications

References 66 publications

A classical trajectory study of the photodissociation of T1 acetaldehyde: The transition from impulsive to statistical dynamics

A classical trajectory study of the photodissociation of T1 acetaldehyde: The transition from impulsive to statistical dynamics

Quantum dynamics of the S+OH→SO+H reaction

On the Detectability of the HSS, HSO, and HOS Radicals in the Interstellar Medium

Contact Info

Product

Resources

About