Ab initio calculations of coupled potential energy surfaces for the Cl(2P3/2,2P1/2)+ H2 reaction

Capecchi, Gabriella; Werner, Hans‐Joachim

doi:10.1039/b411385c

Cited by 74 publications

(109 citation statements)

References 45 publications

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“…23 Although some of the matrix elements do vary significantly in the region of the ground-state barrier, this variation can be safely neglected in this region because the ground-state spin-free surface is well separated from the higher surface there. This is a fairly general phenomenon:…”

Section: 335mentioning

confidence: 99%

“…17 A more complete treatment of SOC involves the inclusion of computed spin-orbit matrix elements, or approximations to them, as functions of the nuclear coordinates, and the construction of the relevant PESs with SOC included. Examples include F( 2 P) + H 2 → HF + H, [18][19][20][21] Cl( 2 P) + H 2 → HCl + H, 22,23 or the symmetric Cl( 2 P) + HCl → HCl + Cl( 2 P) reaction. [24][25][26] Besides the fine-structure splitting, the second important effect of SOC is that it causes spin-forbidden processes to become partially allowed through interaction and mixing of states of different spin multiplicity.…”

Section: Introductionmentioning

confidence: 99%

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A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

Valero

Truhlar

2007

J. Phys. Chem. A

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A diabatic representation is convenient in the study of electronically nonadiabatic chemical reactions because the diabatic energies and couplings are smooth functions of the nuclear coordinates and the couplings are scalar quantities. A method called the fourfold way was devised in our group to generate diabatic representations for spin-free electronic states. One drawback of diabatic states computed from the spin-free Hamiltonian, called a valence diabatic representation, for systems in which spin-orbit coupling cannot be ignored is that the couplings between the states are not zero in asymptotic regions, leading to difficulties in the calculation of reaction probabilities and other properties by semiclassical dynamics methods. Here we report an extension of the fourfold way to construct diabatic representations suitable for spincoupled systems. In this article we formulate the method for the case of even-electron systems that yield pairs of fragments with doublet spin multiplicity. For this type of system, we introduce the further simplification of calculating the triplet diabatic energies in terms of the singlet diabatic energies via Slater's rules and assuming constant ratios of Coulomb to exchange integrals. Furthermore, the valence diabatic couplings in the triplet manifold are taken equal to the singlet ones. An important feature of the method is the introduction of scaling functions, as they allow one to deal with multibond reactions without having to include Comparison of the spin-coupled adiabatic energies obtained from the spin-valence diabatics with those obtained by ab initio calculations with geometry-dependent spin-orbit matrix elements shows that the new method is sufficiently accurate for practical purposes. The method formulated here should be most useful for systems with a large number of atoms, especially heavy atoms, and/or a large number of spin-coupled electronic states.

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Section: 335mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

Valero

Truhlar

2007

J. Phys. Chem. A

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“…For more details on the ab initio determination of the electronically adiabatic and quasidiabatic PESs for ClH 2 , we refer the reader to the earlier papers of Alexander et al 37 and CW. 19 The matrix of the spin-orbit Hamiltonian is determined fully by two components,…”

Section: A Six-state Modelmentioning

confidence: 99%

“…[6][7][8][9][10][11][12][13][14][15][16] These have been based on several potential energy surfaces ͑PESs͒. [17][18][19] To unravel the dependence of the reactivity on the spin-orbit state of the halogen atom, one needs to go beyond the assumption of a single electronically adiabatic PES, which underlies most theoretical simulations of reactive scattering. 4,5,7 The study of nonadiabaticity in reactions of halogens with molecular hydrogen dates back to early work of Tully 20 on the F͑ 2 P 1/2 ͒ +H 2 reaction.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent wavepacket investigation of state-to-state reactive scattering of Cl with para-H2 including the open-shell character of the Cl atom

Zhang

Alexander

2010

The Journal of Chemical Physics

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We describe a time-dependent wavepacket based method for the calculation of the state-to-state cross sections for the Cl+ H 2 reaction including all couplings arising from the nonzero spin and electronic orbital angular momenta of the Cl atom. Reactant-product decoupling allows us to use a physically correct basis in both the reactant and the product arrangements. Our calculated results agree well with the experimental results of Yang and co-workers. We also describe a model with two coupled potential energy surfaces, which includes the spin-orbit coupling, which is responsible for the largest non-Born-Oppenheimer effects in the Cl+ H 2 reaction but neglects the off-diagonal electronically diabatic coupling and all Coriolis couplings due to the electronic spin and orbital angular momenta. The comparison of the results of the full six-state and two-state models with an electronically adiabatic ͑one-state͒ description reveals that the latter describes well the reaction out of the ground spin-orbit state, while the two-state model, which is computationally much faster than the full six-state model, describes well the reaction from both the ground and excited spin-orbit states.

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“…Our group has been studying the details of the infrared-induced chemical reaction, Cl( 2 P 3/2 ) + H 2 (v = 1) → HCl + H, in highly enriched (99.99%) parahydrogen (pH 2 ) crystals at temperatures around 2 K [2][3][4][5]. This prototypical hydrogen abstraction reaction proceeds at these low temperatures via vibrational excitation of the H 2 reagent since the reaction of Cl with H 2 (v = 0) has a ~1900 cm -1 barrier and is + 360 cm -1 endothermic [6][7][8]. To better understand the photochemical mechanism by which infrared (IR) light creates H 2 (v = 1) and triggers the Cl + H 2 reaction, we studied the IR-induced reaction kinetics as a function of the orthohydrogen (oH 2 ) concentration in the solid.…”

Section: Introductionmentioning

confidence: 99%

Infrared studies of ortho-para conversion at Cl-atom and H-atom impurity centers in cryogenic solid hydrogen

Kettwich

Anderson

2010

Low Temperature Physics

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We report infrared spectroscopic studies of H 2 ortho-para (o/p) conversion in solid hydrogen doped with Clatoms at 2 K while the Cl + H 2 (v = 1) → HCl + H infrared-induced chemical reaction is occurring. The Cl-atom doped hydrogen crystals are synthesized using 355 nm in situ photodissociation of Cl 2 precursor molecules. For hydrogen solids with high ortho-H 2 fractional concentrations (X o = 0.55), the o/p conversion kinetics is dominated by Cl-atom catalyzed conversion with a catalyzed conversion rate constant K cc = 1.16 (11)

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Ab initio calculations of coupled potential energy surfaces for the Cl(2P3/2,2P1/2)+ H2 reaction

Cited by 74 publications

References 45 publications

A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

Time-dependent wavepacket investigation of state-to-state reactive scattering of Cl with para-H2 including the open-shell character of the Cl atom

Infrared studies of ortho-para conversion at Cl-atom and H-atom impurity centers in cryogenic solid hydrogen

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