An improved model to calculate equilibrium constants for formation of peroxy radical–water complexes

Shirts, Randall B.; Kumbhani, S.; Burrell, Emily; Hansen, Jaron C.

doi:10.1007/s00214-018-2262-8

Cited by 3 publications

(9 citation statements)

References 34 publications

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“…I have successfully applied this model to one of the vibrational motions of the water dimer and other hydrogen-bonded species. 21 Fitting of the f i (z) functions becomes precarious for m too close to n because f i (z) functions develop singularities at z = 1. I recommend using m ≥ n + 1 except when absolutely necessary.…”

Section: Discussionmentioning

confidence: 99%

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Connecting the Dunham Expansion to the Dissociation Limit for Interatomic Potentials: Application to Lennard-Jones m–n Potentials

Shirts

2018

J. Phys. Chem. A

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Dunham generated the expansion for energy levels of a rotating, vibrating diatomic molecule from an expansion of the potential about the equilibrium position. For partition functions, however, the energy levels are needed all the way to dissociation. Analytic Morse oscillator energies are not very useful because the exponential decay of the Morse potential is much too short-ranged for any physical system. The longer-range Lennard-Jones 12–6 potential could be used, but quantum energies have not previously been conveniently fit. I show how Dunham coefficients begin a set of asymptotic functions for any interaction potential, one function arising from each successive term in the WKB expansion. I apply this to the family of Lennard-Jones m–n (LJ m–n) potentials with an R–m repulsive term and R–n attractive term (m > n) and demonstrate how m can be used as a parameter to adjust either the equilibrium distance or harmonic frequency. I present an empirical parametrization of LJ m–n vibrotor energies starting with Dunham coefficients generated from four terms in the WKB expansion. This information is combined with data from numerically solved energies and asymptotic limits to fit the functions all the way to dissociation. One can also treat exp-6 and similar model potentials with different repulsive parts using the same method because the expansion form is controlled by the long-range part of the potential.

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Section: Discussionmentioning

confidence: 99%

“…In this case, n = 3, and the weak bond and large equilibrium distance of the energy minimum easily put the value of m greater than 5. I have successfully applied this model to one of the vibrational motions of the water dimer and other hydrogen-bonded species …”

Section: Discussionmentioning

confidence: 99%

Connecting the Dunham Expansion to the Dissociation Limit for Interatomic Potentials: Application to Lennard-Jones m–n Potentials

Shirts

2018

J. Phys. Chem. A

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“…It is of interest to quantify the α 2 H for the hydroperoxyl radical using the computational data in order to predict the behavior in a HB environment (solution, troposphere 74 ). It is well known that the computed Δ HB Ss are underestimated values, leading to erroneous Δ HB Gs (and K HB s).…”

Section: Coh/ch + Homentioning

confidence: 99%

Phenolic Hydrogen Transfer by Molecular Oxygen and Hydroperoxyl Radicals. Insights into the Mechanism of the Anthraquinone Process

Korth

2020

J. Org. Chem.

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Hydrogen atom transfer (HAT) by 3 O 2 and HO 2 • from arenols (ArOH), aryloxyls (ArO • ), their tautomers (ArH), and auxiliary compounds has been investigated by means of CBS-QB3 computations. With 3 O 2 , excellent linear correlations have been found between the activation enthalpy and the overall reaction enthalpy. Different pathways have been discerned for HATs involving OH or CH moieties. The results for ArOH + HO 2• → ArO • + H 2 O 2 neither afford a linear correlation nor agree with the experiment. The precise mechanism for the liquid-phase autoxidation of anthrahydroquinone (AnH 2 Q) appears to be not fully understood. A kinetic analysis shows that the HAT by chain-carrying HO 2• occurs with a high rate constant of ≥6 × 10 8 M −1 s −1 (toluene). The second propagation step pertains to a diffusion-controlled HAT by 3 O 2 from the 10-OH-9-anthroxyl radical. Oxanthrone (AnOH) is a more stable tautomer of AnH 2 Q with a ratio of 13 (298 K) in non-hydrogen-bonding (HB) solvents, but the reactivity toward 3 O 2 /HO 2• is much lower. Combination of the computed free energies and Abrahams' HB donating (α 2 H ) and accepting (β 2 H ) parameters has afforded an α 2 H (HO 2 • ) of 0.86 and an α 2 H (H 2 O 2 ) of 0.50.

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“… a Δ E 0K (ZPE corrections included) and Δ G 298K are in kJ/mol. b At the CCSD(T)/6-311++G(2df,2p)//B3LYP/6-311++G(2df,2p) level by Aloisio and Francisco c G3 by Alongi et al d CCSD(T)/6-311++G(2df,p)//MP2(Full)/6-311++G(2df,p) by Clark et al e At the F12/VTZ-F12//M06-2X/AVTZ level by Zhang et al f By Shirts et al g By Kanno et al …”

Section: Resultsmentioning

confidence: 99%

“…Water can form more stable complexes with peroxy radicals containing hydroxyl and carbonyl moieties through hydrogen bonds. A number of theoretical studies have predicted the existence of water complexes with peroxy radicals and estimated the equilibrium constants for the formation reactions. − With the calculated equilibrium constants for RO 2 ·H 2 O complexes, model studies suggested that RO 2 ·H 2 O complexes may take up a substantial amount of peroxy radicals a on global scale, particularly for isoprene-derived RO 2 radicals . The complexation between water and peroxy radicals may affect the kinetics of peroxy radicals, which has not taken into account yet by current atmospheric chemistry models, due in part to the difficulty of acquiring reliable thermodynamic and kinetic parameters.…”

Section: Introductionmentioning

confidence: 99%

Computational Study on the Reaction of β-Hydroxyethylperoxy Radical with HO₂ and Effects of Water Vapor

Wang

2022

J. Phys. Chem. A

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The reaction of β-hydroxyethylperoxy radical (β-HEP) and HO 2 with and without water was studied using quantum chemistry and kinetic calculations. The main products are HOCH 2 CH 2 OOH and 3 O 2 for the reaction with and without water, while all other reaction channels can be neglected. The rate coefficients of the reaction follow negative temperature dependence. The pseudo-second-order rate coefficients are 2−4 orders of magnitude smaller for the reaction with saturated water vapor, indicating the negligible contribution of water in this reaction. This is probably also true for other peroxy radicals (except for HO 2 ), indicating that a large part of previous results on the water enhancement of reaction rate coefficients might have overestimated the influence of water.

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An improved model to calculate equilibrium constants for formation of peroxy radical–water complexes

Cited by 3 publications

References 34 publications

Connecting the Dunham Expansion to the Dissociation Limit for Interatomic Potentials: Application to Lennard-Jones m–n Potentials

Connecting the Dunham Expansion to the Dissociation Limit for Interatomic Potentials: Application to Lennard-Jones m–n Potentials

Phenolic Hydrogen Transfer by Molecular Oxygen and Hydroperoxyl Radicals. Insights into the Mechanism of the Anthraquinone Process

Computational Study on the Reaction of β-Hydroxyethylperoxy Radical with HO₂ and Effects of Water Vapor

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An improved model to calculate equilibrium constants for formation of peroxy radical–water complexes

Cited by 3 publications

References 34 publications

Connecting the Dunham Expansion to the Dissociation Limit for Interatomic Potentials: Application to Lennard-Jones m–n Potentials

Connecting the Dunham Expansion to the Dissociation Limit for Interatomic Potentials: Application to Lennard-Jones m–n Potentials

Phenolic Hydrogen Transfer by Molecular Oxygen and Hydroperoxyl Radicals. Insights into the Mechanism of the Anthraquinone Process

Computational Study on the Reaction of β-Hydroxyethylperoxy Radical with HO2 and Effects of Water Vapor

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Computational Study on the Reaction of β-Hydroxyethylperoxy Radical with HO₂ and Effects of Water Vapor