Computational Methods for Polyatomic Bimolecular Reactions

Schatz, George C.; Horst, Marc ter; Takayanagi, Toshiyuki

doi:10.1142/9789812812162_0001

Cited by 14 publications

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“…The HOD product vibrational actions were determined at the end of each reactive trajectory using the Fourier series method. , The coordinates and momenta of HOD are calculated as a function of time, integrating the classical equations of motion for the isolated triatomic during ∼1 ps, i.e., in the same manner as during the calculation but with the collision partner (D atom) removed. Once the coordinates and momenta are expanded in Fourier series, the noninteger vibrational quantum numbers, N k ′ ( k = 1–3), which correspond to the good classical actions, are calculated using the corresponding equations.…”

Section: Methodsmentioning

confidence: 99%

Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D₂ → HOD(v₁′,v₂′,v₃′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

2011

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The angle-velocity and product vibrational state distributions for the OH + D(2) reaction at a collision energy of 0.28 eV have been calculated using the quasi-classical trajectory-gaussian binning (QCT-GB) method and the Wu-Schatz-Lendvay-Fang-Harding (WSLFH) analytical potential energy surface. Comparison with high resolution molecular beam experiments shows that, differing from what happens when using the standard QCT method (i.e., histogram binning), very good results are obtained for both distributions. Hence, the strong differences previously observed between QCT and experimental results mainly come from an inadequate pseudoquantization of HOD rather than from other quantum effects. This is probably the first time that such a high level of agreement between theory and high resolution experimental data has been found in polyatomic reaction dynamics.

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Section: Methodsmentioning

confidence: 99%

Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D₂ → HOD(v₁′,v₂′,v₃′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

2011

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“…The RLU model has its origins in the “rotating linear model” for chemical reactions . There have been several reviews of quantum scattering calculations for polyatomic systems. ,− …”

Section: Quantum Calculation Of the S Matrix Elements And Full Differ...mentioning

confidence: 99%

Angular Scattering Dynamics of the CH₄ + Cl → CH₃ + HCl Reaction Using Nearside–Farside, Local Angular Momentum, and Resummation Theories

2015

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The differential cross section (DCS) for the CH4 + Cl → CH3 + HCl reaction is studied at six total energies where all of the species are in their ground states. The scattering (S) matrix elements have been calculated by the rotating line umbrella method for a dual-level ab initio analytic potential energy surface. We make the first application to this reaction of nearside-farside (NF) and local angular momentum (LAM) techniques, including resummation orders (r) of 0, 1, 2, and 3 for the partial-wave series representation of the full scattering amplitude. We find that resummation usually cleans the NF r = 0 DCSs of unphysical oscillations, especially at small angles. This cleaning effect is typically most pronounced when changing from no resummation (r = 0) to r = 1; further resummations from r = 1 to r = 2 and from r = 2 to r = 3 have smaller effects. The NF DCS analyses show that the reaction is N-dominated at sideward and large angles, whereas at small angles there are oscillations caused by NF interference. The NF LAM analysis provides consistent and complementary information, in particular for the total angular momenta that contribute to the reaction at different scattering angles. The NF analyses also provide justification for simpler N-dominant dynamical theories such as the semiclassical optical model, which provides an explanation for the distorted mirror image effect for the moduli of the S matrix elements and the DCSs, as well as the use of a hard-sphere DCS over limited angular ranges.

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“…(30)(31)(32)(33) Semiclassical eigenvalues as defined by the EBK formula are not accurate enough to be of use in interpreting spectroscopic measurements, but are good for qualitative interpretation of intramolecular dynamics, and they are also used in trajectory studies of bimolecular collisions^) (where they define the vibrational states of the reactant and product molecules).…”

Section: Dynamics Of Highly Excited States In Chemistrymentioning

confidence: 99%

“…Schatz et al (30) and Takayanagi and Schatz (103) have recently compared QCT results and reduced dimensionality quantum scattering results for the reaction CN + H 2 -HCN + H, including an analysis of the product vibrational distributions in the HCN product. This is the reverse of the type of reaction that we are considering here, but the comparison is still useful.…”

Section: Excitation Of Reagentsmentioning

confidence: 99%

“…Although there are numerous methods for using quantum scattering theory to describe bimolecular reactions, only a small group of these methods have been used to describe reactions involving excited triatomic and larger molecules at the state-resolved level. An extensive review of these methods has recently been given (30), so we will only present a brief discussion here.…”

Section: Excitation Of Reagentsmentioning

confidence: 99%

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Dynamics of Highly Excited States in Chemistry: An Overview

Mullin

Schatz²

1997

ACS Symposium Series

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This article provides an overview of chemical research that is concerned with the dynamics of highly excited states of molecules. Four broad topics are discussed, including (1) highly excited bound vibrational states of polyatomic molecules, (2) unimolecular decay of highly excited molecules, (3) collisional relaxation of highly excited polyatomic molecules, and (4) bimolecular reactions involving vibrationally excited molecules. For each topic, we present an overview of current experimental and theoretical research being done, along with a brief discussion of selected applications.Highly excited states of molecules are important in many areas of chemistry, including photochemistry, reaction kinetics and spectroscopy. The dynamics of highly excited states in chemical processes is often quite complex, but at the same time is amenable to detailed experimental and theoretical study, and as a result the interplay between theory and experiment plays an important role. Excited state dynamics often involve intermolecular and/or intramolecular energy flow between many different kinds of motions (vibrational, rotational, translational, electronic) that span a wide range of time scales. As a result, there are many different kinds of experiments that can be brought to bear on these problems, including frequency and time-resolved spectroscopy, state-resolved kinetics, energy transfer measurements and pump-probe laser experiments. Many of these experiments require close coupling to theoretical modelling to optimize interpretation. The theoretical description of these processes can be done in many ways, including theories based on classical and quantum mechanics, statistical approximations and dynamical models. In addition, many of the theoretical applications require close interplay between electronic structure theory (for determining potential energy surfaces and surface couplings) and theories of dynamical processes (which use the surfaces to calculate measurable properties). As a result, many parts of the theoretical and experimental chemistry community are brought together in these studies.This article considers experimental and theoretical work related to the description of highly excited states in four broad areas: highly excited bound vibrational states, unimolecular decay, collisional energy transfer and bimolecular reactions. For 2

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Computational Methods for Polyatomic Bimolecular Reactions

Cited by 14 publications

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Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D₂ → HOD(v₁′,v₂′,v₃′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D₂ → HOD(v₁′,v₂′,v₃′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

Angular Scattering Dynamics of the CH₄ + Cl → CH₃ + HCl Reaction Using Nearside–Farside, Local Angular Momentum, and Resummation Theories

Dynamics of Highly Excited States in Chemistry: An Overview

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Computational Methods for Polyatomic Bimolecular Reactions

Cited by 14 publications

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Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D2 → HOD(v1′,v2′,v3′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D2 → HOD(v1′,v2′,v3′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

Angular Scattering Dynamics of the CH4 + Cl → CH3 + HCl Reaction Using Nearside–Farside, Local Angular Momentum, and Resummation Theories

Dynamics of Highly Excited States in Chemistry: An Overview

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Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D₂ → HOD(v₁′,v₂′,v₃′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D₂ → HOD(v₁′,v₂′,v₃′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

Angular Scattering Dynamics of the CH₄ + Cl → CH₃ + HCl Reaction Using Nearside–Farside, Local Angular Momentum, and Resummation Theories