Ab initio reaction paths and direct dynamics calculations

Baldridge, Kim K.; Gordon, Mark S.; Steckler, Rozeanne; Truhlar, Donald G.

doi:10.1021/j100350a018

Cited by 357 publications

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“…56 Minima were confirmed by a positive definite Hessian, whereas transition states have one and only one negative Hessian eigenvalue. Intrinsic reaction coordinate calculations [57][58][59][60][61] (IRC) were conducted to connect the located transition state with the corresponding minima. A least linear motion path method was used to obtain an initial guess of the transition state structure.…”

Section: Methodsmentioning

confidence: 99%

Catalytic Role for Water in the Atmospheric Production of ClNO

et al. 2010

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High level ab initio calculations of clusters comprised of water, HCl, and ON-ONO2 are used to study nitrosyl chloride (ClNO) formation in gas phase water clusters, which are also mimics for thin water films present at environmental interfaces. Two pathways are considered, direct formation from the reaction of gaseous HCl with ON-ONO2 and an indirect pathway involving the hydrolysis of ON-ONO2 to form HONO, followed by the reaction of HONO with HCl to form ClNO. Surprisingly, direct formation of ClNO is found to be the dominant channel in the presence of water despite the possibility of a competing hydrolysis of ON-ONO2 to form HONO. A single water molecule effectively catalyzes the ON-ONO2 + HCl reaction, and in the presence of two or more water molecules the reaction to form ClNO becomes spontaneous. Direct formation of ClNO is fast at room and ice temperatures, indicating the possible significance of this pathway for chlorine activation chemistry in both the polar and midlatitude troposphere, in volcanic plumes and indoors. The reaction enthalpies, activation energies, and rate constants for all studied reactions are reported. The results are discussed in light of recent experiments. Disciplines Chemistry CommentsReprinted (adapted) Jerusalem, 91904, Israel ReceiVed: December 24, 2009; ReVised Manuscript ReceiVed: February 21, 2010 High level ab initio calculations of clusters comprised of water, HCl, and ON-ONO 2 are used to study nitrosyl chloride (ClNO) formation in gas phase water clusters, which are also mimics for thin water films present at environmental interfaces. Two pathways are considered, direct formation from the reaction of gaseous HCl with ON-ONO 2 and an indirect pathway involving the hydrolysis of ON-ONO 2 to form HONO, followed by the reaction of HONO with HCl to form ClNO. Surprisingly, direct formation of ClNO is found to be the dominant channel in the presence of water despite the possibility of a competing hydrolysis of ON-ONO 2 to form HONO. A single water molecule effectively catalyzes the ON-ONO 2 + HCl reaction, and in the presence of two or more water molecules the reaction to form ClNO becomes spontaneous. Direct formation of ClNO is fast at room and ice temperatures, indicating the possible significance of this pathway for chlorine activation chemistry in both the polar and midlatitude troposphere, in volcanic plumes and indoors. The reaction enthalpies, activation energies, and rate constants for all studied reactions are reported. The results are discussed in light of recent experiments.

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Section: Methodsmentioning

confidence: 99%

Catalytic Role for Water in the Atmospheric Production of ClNO

et al. 2010

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“…Although the calculations reported here are based on an analytic potential energy surface, the method can be used equally well with direct dynamics (50)(51)(52)(53).…”

Section: Resultsmentioning

confidence: 99%

Quantum mechanical reaction rate constants by vibrational configuration interaction: The OH + H₂→H₂O + H reaction as a function of temperature

Chakraborty

Truhlar

2005

Proc. Natl. Acad. Sci. U.S.A.

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The thermal rate constant of the 3D OH ؉ H23 H2O ؉ H reaction was computed by using the flux autocorrelation function, with a time-independent square-integrable basis set. Two modes that actively participate in bond making and bond breaking were treated by using 2D distributed Gaussian functions, and the remaining (nonreactive) modes were treated by using harmonic oscillator functions. The finite-basis eigenvalues and eigenvectors of the Hamiltonian were obtained by solving the resulting generalized eigenvalue equation, and the flux autocorrelation function for a dividing surface optimized in reduced-dimensionality calculations was represented in the basis formed by the eigenvectors of the Hamiltonian. The rate constant was obtained by integrating the flux autocorrelation function. The choice of the final time to which the integration is carried was determined by a plateau criterion. The potential energy surface was from Wu, Schatz, Lendvay, Fang, and Harding (WSLFH). We also studied the collinear H ؉ H2 reaction by using the Liu-Siegbahn-Truhlar-Horowitz (LSTH) potential energy surface. The calculated thermal rate constant results were compared with reported values on the same surfaces. The success of these calculations demonstrates that time-independent vibrational configuration interaction can be a very convenient way to calculate converged quantum mechanical rate constants, and it opens the possibility of calculating converged rate constants for much larger reactions than have been treated until now.flux autocorrelation ͉ chemical kinetics ͉ dynamics ͉ localized basis functions ͉ many-body problem T he evaluation of the thermal reaction rate constant k(T) from the quantum mechanical flux provides an efficient alternative to the computation of rate constants by means of the scattering matrix. The quantum mechanical formulation of k(T) in terms of flux autocorrelation functions C f (t) was presented by Yamamoto (1) and Miller et al. (2,3), and there have been several applications to calculate thermal rate constants for specific systems. The flux operator can be used to compute the cumulative reaction probability N(E) or the flux autocorrelation function, and either of these functions can be used to compute the thermal rate constant. Various approaches (4-24) involving basis functions, path integrals, and wave packet propagation methods have been used. Recently, Manthe and coworkers (19,22) have calculated the thermal rate constants for the CH 4 ϩ H3CH 3 ϩ H 2 and CH 4 ϩ O3CH 3 ϩ OH reactions by calculating N(E) as a function of energy E by using the multiconfiguration time-dependent Hartree (MCTDH) method. Earlier work on triatomic reactions showed that accurate results can be obtained with an approach based on diagonalizing the time-independent Hamiltonian (4, 8, 10). One advantage of this formulation is that the variational principle is used to identify the relevant subspace of the basis set. This approach is appealing in terms of its generality and straightforward extension to larger systems, and it is exte...

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“…The IRC algorithm (Baldridge et al 1989;Deng et al 1993;Deng & Ziegler 1994), as implemented in GAMESS, was used to connect the reactants (acetylene and O 2 ) to the product (cyclopropenone). Using the obtained B3LYP structures, the transition state, reactants, and product energies were refined with single point CR-CCL calculations.…”

Section: Computational Detailsmentioning

confidence: 99%

SPIN-FORBIDDEN AND SPIN-ALLOWED CYCLOPROPENONE (c-H₂C₃O) FORMATION IN INTERSTELLAR MEDIUM

Ahmadvand

Zaari

Varganov

2014

ApJ

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Three proposed mechanisms of cyclopropenone (c-H 2 C 3 O) formation from neutral species are studied using highlevel electronic structure methods in combination with nonadiabatic transition state and collision theories to deduce the likelihood of each reaction mechanism under interstellar conditions. The spin-forbidden reaction involving the singlet electronic state of cyclopenylidene (c-C 3 H 2 ) and the triplet state of atomic oxygen is studied using nonadiabatic transition state theory to predict the rate constant for c-H 2 C 3 O formation. The spin-allowed reactions of c-C 3 H 2 with molecular oxygen and acetylene with carbon monoxide were also investigated. The reaction involving the ground electronic states of acetylene and carbon monoxide has a very large reaction barrier and is unlikely to contribute to c-H 2 C 3 O formation in interstellar medium. The spin-forbidden reaction of c-C 3 H 2 with atomic oxygen, despite the high probability of nonadiabatic transition between the triplet and singlet states, was found to have a very small rate constant due to the presence of a small (3.8 kcal mol −1 ) reaction barrier. In contrast, the spin-allowed reaction between c-C 3 H 2 and molecular oxygen is found to be barrierless, and therefore can be an important path to the formation of c-H 2 C 3 O molecule in interstellar environment.

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Ab initio reaction paths and direct dynamics calculations

Cited by 357 publications

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Catalytic Role for Water in the Atmospheric Production of ClNO

Catalytic Role for Water in the Atmospheric Production of ClNO

Quantum mechanical reaction rate constants by vibrational configuration interaction: The OH + H₂→H₂O + H reaction as a function of temperature

SPIN-FORBIDDEN AND SPIN-ALLOWED CYCLOPROPENONE (c-H₂C₃O) FORMATION IN INTERSTELLAR MEDIUM

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Ab initio reaction paths and direct dynamics calculations

Cited by 357 publications

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Catalytic Role for Water in the Atmospheric Production of ClNO

Catalytic Role for Water in the Atmospheric Production of ClNO

Quantum mechanical reaction rate constants by vibrational configuration interaction: The OH + H2→H2O + H reaction as a function of temperature

SPIN-FORBIDDEN AND SPIN-ALLOWED CYCLOPROPENONE (c-H2C3O) FORMATION IN INTERSTELLAR MEDIUM

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Quantum mechanical reaction rate constants by vibrational configuration interaction: The OH + H₂→H₂O + H reaction as a function of temperature

SPIN-FORBIDDEN AND SPIN-ALLOWED CYCLOPROPENONE (c-H₂C₃O) FORMATION IN INTERSTELLAR MEDIUM