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Agarwal A, Boruah PJ, Ahamed SS, Baruah S, Paul AK. Post-Transition State Direct Dynamics Simulations on the Ozonolysis of Catechol in an N 2 Bath and Comparison with Gas-Phase Results. J Phys Chem A 2023; 127:6804-6815. [PMID: 37531625 DOI: 10.1021/acs.jpca.3c03326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Chemical dynamics simulations on the post-transition state dynamics of ozonolysis of catechol are performed in this article using a newly developed QM + MM simulation model. The reaction is performed in a bath of N2 molecules equilibrated at 300 K. Two bath densities, namely, 20 and 324 kg/m3, are considered for the simulation. The excitation temperatures of a catechol-O3 moiety are taken as 800, 1000, and 1500 K for each density. At these new excitation temperatures, the gas-phase results are also computed to compare the results and quantify the effect of surrounding molecules on this reaction. Like the previous findings, five reaction channels are observed in the present investigation, producing CO2, CO, O2, small carboxylic acid (SCA), and H2O. The probabilities of these products are discussed with the role of bath densities. Results from the gas-phase simulation and density of 20 kg/m3 are very similar, whereas results differ significantly at a higher bath density of 324 kg/m3. The rate constants for the unimolecular channel at each temperature and density are also calculated and reported. The QM + MM setup used here can also be used for other chemical reactions, where the solvent effect is important.
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Affiliation(s)
- Ankita Agarwal
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, Meghalaya, India
| | - Palash Jyoti Boruah
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, Meghalaya, India
| | - Sk Samir Ahamed
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, Meghalaya, India
| | - Shrutimala Baruah
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, Meghalaya, India
| | - Amit Kumar Paul
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, Meghalaya, India
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2
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Jasper A. Predicting third-body collision efficiencies for water and other polyatomic baths. Faraday Discuss 2022; 238:68-86. [DOI: 10.1039/d2fd00038e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Low-pressure-limit microcanonical (collisional activation) and thermal rate constants are predicted using a combination of automated ab initio potential energy surface construction, classical trajectories, transition state theory, and a detailed kinetic...
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Hren ZR, Lazarock CR, Vincent TA, Rivera-Rivera LA, Wagner AF. Pressure Effects on the Relaxation of an Excited Ethane Molecule in High-Pressure Bath Gases. J Phys Chem A 2021; 125:8680-8690. [PMID: 34582214 DOI: 10.1021/acs.jpca.1c05838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We use molecular dynamics to calculate the rotational and vibrational energy relaxation of C2H6 in Ar, Kr, and Xe bath gases over a pressure range of 10-400 atm and at temperatures of 300 and 800 K. The C2H6 is instantaneously excited by 80 kcal/mol randomly distributed into both vibrational and rotational modes. The computed relaxation rates show little sensitivity to the identity of the noble gas in the bath. Vibrational relaxation rates show a nonlinear pressure dependence at 300 K. At 800 K the reduced range of bath gas densities covered by the range of pressures does not yet show any nonlinearity in the pressure dependence. Rotational relaxation is characterized with two relaxation rates. The slower rate is comparable to the vibrational relaxation rate. The faster rate has a linear pressure dependence at 300 K but an irregular, nonlinear pressure dependence at 800 K. To understand this, a model was developed based on approximating the periodic box used in the molecular dynamics simulations by an equal-volume collection of cubes where each cube is sized to allow only single occupancy by the noble gas or the molecule. Combinatorial statistics then leads to a pressure- and temperature-dependent analytic distribution of the bath gas species the molecule encounters in a collision. This distribution, the dissociation energy of molecule/bath gas complexes and bath gas clusters, and the computed energy release per collision combine to show that only at 300 K is the energy release sufficient to dissociate likely complexes and clusters. This suggests that persistent and pressure-dependent clusters and complexes at 800 K may be responsible for the nonlinear pressure dependence of rotational relaxation.
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Affiliation(s)
- Zackary R Hren
- Department of Physical Sciences, Ferris State University, Big Rapids, Michigan 49307, United States
| | - Chad R Lazarock
- Department of Physical Sciences, Ferris State University, Big Rapids, Michigan 49307, United States
| | - Tasha A Vincent
- Department of Physical Sciences, Ferris State University, Big Rapids, Michigan 49307, United States
| | - Luis A Rivera-Rivera
- Department of Physical Sciences, Ferris State University, Big Rapids, Michigan 49307, United States
| | - Albert F Wagner
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Ahamed SS, Kim H, Paul AK, West NA, Winner JD, Donzis DA, North SW, Hase WL. Comparison of intermolecular energy transfer from vibrationally excited benzene in mixed nitrogen-benzene baths at 140 K and 300 K. J Chem Phys 2020; 153:144116. [PMID: 33086796 DOI: 10.1063/5.0021293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Gas phase intermolecular energy transfer (IET) is a fundamental component of accurately explaining the behavior of gas phase systems in which the internal energy of particular modes of molecules is greatly out of equilibrium. In this work, chemical dynamics simulations of mixed benzene/N2 baths with one highly vibrationally excited benzene molecule (Bz*) are compared to experimental results at 140 K. Two mixed bath models are considered. In one, the bath consists of 190 N2 and 10 Bz, whereas in the other bath, 396 N2 and 4 Bz are utilized. The results are compared to results from 300 K simulations and experiments, revealing that Bz*-Bz vibration-vibration IET efficiency increased at low temperatures consistent with longer lived "chattering" collisions at lower temperatures. In the simulations, at the Bz* excitation energy of 150 kcal/mol, the averaged energy transferred per collision, ⟨ΔEc⟩, for Bz*-Bz collisions is found to be ∼2.4 times larger in 140 K than in 300 K bath, whereas this value is ∼1.3 times lower for Bz*-N2 collisions. The overall ⟨ΔEc⟩, for all collisions, is found to be almost two times larger at 140 K compared to the one obtained from the 300 K bath. Such an enhancement of IET efficiency at 140 K is qualitatively consistent with the experimental observation. However, the possible reasons for not attaining a quantitative agreement are discussed. These results imply that the bath temperature and molecular composition as well as the magnitude of vibrational energy of a highly vibrationally excited molecule can shift the overall timescale of rethermalization.
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Affiliation(s)
- Sk Samir Ahamed
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, India
| | - Hyunsik Kim
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
| | - Amit K Paul
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, India
| | - Niclas A West
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Joshua D Winner
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Diego A Donzis
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Simon W North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - William L Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
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Ahamed SS, Kumar P, Kalita H, Paul AK. Mode‐to‐Mode Collision Energy Transfer from Vibrationally Excited C
6
F
6
to NO/N
2
Mixed Bath with the Development of New Potential Energy Functions. ChemistrySelect 2020. [DOI: 10.1002/slct.202002600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sk. Samir Ahamed
- Department of Chemistry National Institute of Technology Meghalaya Shillong Meghalaya 793003 INDIA
| | - Pavan Kumar
- Department of Chemistry National Institute of Technology Meghalaya Shillong Meghalaya 793003 INDIA
| | - Hrishikesh Kalita
- Department of Chemistry National Institute of Technology Meghalaya Shillong Meghalaya 793003 INDIA
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati Assam 781039 INDIA
| | - Amit K. Paul
- Department of Chemistry National Institute of Technology Meghalaya Shillong Meghalaya 793003 INDIA
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Rivera‐Rivera LA, Wagner AF. Mode‐specific pressure effects on the relaxation of an excited nitromethane molecule in an argon bath. INT J CHEM KINET 2020. [DOI: 10.1002/kin.21415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
| | - Albert F. Wagner
- Chemical Sciences and Engineering Division Argonne National Laboratory Argonne IL 60439 USA
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Roytman VA, Singleton DA. Solvation Dynamics and the Nature of Reaction Barriers and Ion-Pair Intermediates in Carbocation Reactions. J Am Chem Soc 2020; 142:12865-12877. [DOI: 10.1021/jacs.0c06295] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Vladislav A. Roytman
- Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842, United States
| | - Daniel A. Singleton
- Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842, United States
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Jasper AW. Microcanonical Rate Constants for Unimolecular Reactions in the Low-Pressure Limit. J Phys Chem A 2020; 124:1205-1226. [DOI: 10.1021/acs.jpca.9b10693] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ahren W. Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Ahamed SS, Mahanta H, Paul AK. A Competition between Dissociation Pathway and Energy Transfer Pathway: Unimolecular Dissociation of a Benzene-Hexafluorobenzene Complex in Nitrogen Bath. J Phys Chem A 2019; 123:10663-10675. [PMID: 31755713 DOI: 10.1021/acs.jpca.9b07258] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The unimolecular dissociation of a benzene-hexafluorobenzene complex at 1000, 1500, and 2000 K is studied inside a bath of 1000 N2 molecules kept at 300 K using chemical dynamics simulation. Three bath densities of 20, 324, and 750 kg/m3 are considered. The dissociation dynamics of the complex at a 20 kg/m3 bath density is found to be similar to that in the gas phase, whereas the dynamics is drastically different at higher bath densities. The microcanonical/canonical dissociation rate constants for the three bath densities are calculated and fitted to the Arrhenius equation. The activation energies are found to be similar to the gas-phase one. However, the pre-exponential factor is lower and decreases with the increase in bath density. The vibrational degree of freedom of the complex more effectively participates in the collisional energy transfer to the N2 bath, whereas the translational and rotational degrees of freedom of N2 receive the transferred energy. The energy transfer efficiency increases with the increase in bath density. The time scale of the energy transfer pathway is more than that of the dissociation pathway, and negligible direct dissociation of the complex is observed from the simulation at the highest bath density.
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Affiliation(s)
- Sk Samir Ahamed
- Department of Chemistry , National Institute of Technology Meghalaya , Shillong 793003 , Meghalaya , India
| | - Himashree Mahanta
- Department of Chemistry , National Institute of Technology Meghalaya , Shillong 793003 , Meghalaya , India
| | - Amit K Paul
- Department of Chemistry , National Institute of Technology Meghalaya , Shillong 793003 , Meghalaya , India
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Ahamed SS, Mahanta H, Paul AK. Unimolecular dissociation of C6H6-C6F6 complex in N2 bath and comparison with gas phase dynamics. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.06.063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Rivera-Rivera LA, Wagner AF, Perry JW. Normal mode analysis on the relaxation of an excited nitromethane molecule in argon bath. J Chem Phys 2019; 151:034303. [PMID: 31325951 DOI: 10.1063/1.5099050] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In our previous work [Rivera-Rivera et al., J. Chem. Phys. 142, 014303 (2015)], classical molecular dynamics simulations followed the relaxation, in a 300 K Ar bath at a pressure of 10-400 atm, of nitromethane (CH3NO2) instantaneously excited by statistically distributing 50 kcal/mol among all its internal degrees of freedom. Both rotational and vibrational energies decayed with nonexponential curves. The present work explores mode-specific mechanisms at work in the decay process. With the separation of rotation and vibration developed by Rhee and Kim [J. Chem. Phys. 107, 1394 (1997)], one can show that the vibrational kinetic energy decomposes only into vibrational normal modes, while the rotational and Coriolis energies decompose into both vibrational and rotational normal modes. The saved CH3NO2 positions and momenta were converted into mode-specific energies whose decay was monitored over 1000 ps. The results identify vibrational and rotational modes that promote/resist energy lost and drive nonexponential behavior.
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Affiliation(s)
- Luis A Rivera-Rivera
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA
| | - Albert F Wagner
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Jamin W Perry
- Department of Chemistry, Baker University, Baldwin City, Kansas 66006, USA
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Jasper AW, Davis MJ. Parameterization Strategies for Intermolecular Potentials for Predicting Trajectory-Based Collision Parameters. J Phys Chem A 2019; 123:3464-3480. [DOI: 10.1021/acs.jpca.9b01918] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ahren W. Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Michael J. Davis
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Mahanta H, Baishya D, Ahamed SS, Paul AK. A Better Understanding of the Unimolecular Dissociation Dynamics of Weakly Bound Aromatic Compounds at High Temperature: A Study on C 6H 6-C 6F 6 and Comparison with C 6H 6 Dimer. J Phys Chem A 2019; 123:2517-2526. [PMID: 30848910 DOI: 10.1021/acs.jpca.8b12188] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chemical dynamics simulations are performed to study the unimolecular dissociation of the benzene (Bz)-hexafluorobenzene (HFB) complex at five different temperatures ranging from 1000 to 2000 K, and the results are compared with that of the Bz dimer at common simulation temperatures. Bz-HFB, in comparison with Bz dimer, possesses a much attractive intermolecular interaction, a very different equilibrium geometry, and a lower average quantum vibrational excitation energy at a given temperature. Six low-frequency modes of Bz-HFB are formed by Bz + HFB association which are weakly coupled with the vibrational modes of Bz and HFB. However, this coupling is found much stronger in Bz-HFB compared to the same in the Bz dimer. The simulations are done with very good potential energy parameters taken from the literature. Considering the canonical (TST) model, the unimolecular dissociation rate constant at each temperature is calculated and fitted to the Arrhenius equation. An activation energy of 5.0 kcal/mol and a pre-exponential factor of 2.39 × 1012 s-1 are obtained, which are of expected magnitudes. The responsible vibrational mode for dissociation is identified by performing normal-mode analysis. Simulations with random excitations of high-frequency Bz and HFB modes and low-frequency inter-Bz-HFB vibrational modes of the Bz-HFB complex are also performed. The intramolecular vibrational energy redistribution (IVR) time and the unimolecular dissociation rate constants are calculated from these simulations. The latter shows good agreement with the same obtained from simulation with random excitation of all vibrational modes.
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Affiliation(s)
- Himashree Mahanta
- Department of Chemistry , National Institute of Technology Meghalaya , Shillong 793003 , Meghalaya , India
| | - Daradi Baishya
- Department of Chemistry , National Institute of Technology Meghalaya , Shillong 793003 , Meghalaya , India
| | - Sk Samir Ahamed
- Department of Chemistry , National Institute of Technology Meghalaya , Shillong 793003 , Meghalaya , India
| | - Amit K Paul
- Department of Chemistry , National Institute of Technology Meghalaya , Shillong 793003 , Meghalaya , India
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