Partial widths of feshbach funnel resonances in the Na(3p) � H2 exciplex

Mielke, Steven L.; Tawa, Gregory J.; Truhlar, Donald G.; Schwenke, David W.

doi:10.1002/qua.560480856

Cited by 18 publications

(18 citation statements)

References 33 publications

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“…A transition to the ground state PES causes a dissociation of the complex into Na(3p) and rovibrationally highly excited H 2 . These results, as first deduced from qualitative considerations on static potential energy surfaces, could be confirmed by dynamical calculations [167,[172][173][174][175][176][177][178][179] and experiments [156]. The non-adiabatic crossing between the two PES in Fig.…”

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confidence: 75%

Evolutionary algorithms and their application to optimal control studies

et al. 2001

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supporting

confidence: 75%

Evolutionary algorithms and their application to optimal control studies

et al. 2001

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“…The initial such application was the nonreactive quenching process Na(3p) þ H 2 ! Na(3s) þ H 2 for zero [62][63][64][65] and unit 65 total angular momentum using a two-state representation of the NaH 2 system. Accurate quantum mechanical calculations were also carried out 66 for the spin-orbit-coupled collisions H þ HBr !…”

Section: Quantum Mechanical Dynamicsmentioning

confidence: 99%

Introductory lecture: Nonadiabatic effects in chemical dynamics

et al. 2004

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Recent progress in the theoretical treatment of electronically nonadiabatic processes is discussed. First we discuss the generalized Born-Oppenheimer approximation, which identifies a subset of strongly coupled states, and the relative advantages and disadvantages of adiabatic and diabatic representations of the coupled surfaces and their interactions are considered. Ab initio diabatic representations that do not require tracking geometric phases or calculating singular nonadiabatic nuclear momentum coupling will be presented as one promising approach for characterizing the coupled electronic states of polyatomic photochemical systems. Such representations can be accomplished by methods based on functionals of the adiabatic electronic density matrix and the identification of reference orbitals for use in an overlap criterion. Next, four approaches to calculating or modeling electronically nonadiabatic dynamics are discussed: (1) accurate quantum mechanical scattering calculations, (2) approximate wave packet methods, (3) surface hopping, and (4) self-consistent-potential semiclassical approaches. The last two of these are particularly useful for polyatomic photochemistry, and recent refinements of these approaches will be discussed. For example, considerable progress has been achieved in making the surface hopping method more applicable to the study of systems with weakly coupled electronic states. This includes introducing uncertainty principle considerations to alleviate the problem of classically forbidden surface hops and the development of an efficient sampling algorithm for low-probability events. A topic whose central importance in a number of quantum mechanical fields is becoming more widely appreciated is the introduction of decoherence into the quantal degrees of freedom to account for the effect of the classical treatment on the other degrees of freedom, and we discuss how the introduction of such decoherence into a self-consistent-potential approximation leads to a reasonably accurate but very practical trajectory method for electronically nonadiabatic processes. Finally, the performances of several dynamical methods for Landau-Zener-type and Rosen-Zener-Demkov-type reactive scattering problems are compared.

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“…These states show up in scattering calculations as electronic Feshbach resonances . We will call them Feshbach funnel resonances , We summarize the process here.…”

Section: Quantum Mechanical Theorymentioning

confidence: 99%

Quantum Mechanical and Quasiclassical Trajectory Surface Hopping Studies of the Electronically Nonadiabatic Predissociation of the Ã State of NaH₂

et al. 1999

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Fully coupled quantum mechanical scattering calculations and adiabatic uncoupled bound-state calculations are used to identify Feshbach funnel resonances that correspond to long-lived exciplexes in the Ã state of NaH2, and the scattering calculations are used to determine their partial and total widths. The total widths determine the lifetimes, and the partial widths determine the branching probabilities for competing decay mechanisms. We compare the quantum mechanical calculations of the resonance lifetimes and the average final vibrational and rotational quantum numbers of the decay product, H2(ν‘, j‘), to trajectory surface hopping calculations carried out by various prescriptions for the hopping event. Tully's fewest switches algorithm is used for the trajectory surface hopping calculations, and we present a new strategy for adaptive stepsize control that dramatically improves the convergence of the numerical propagation of the solution of the coupled classical and quantum mechanical differential equations. We performed the trajectory surface hopping calculations with four prescriptions for the hopping vector that is used for adjusting the momentum at hopping events. These include changing the momentum along the nonadiabatic coupling vector (d), along the gradient of the difference in the adiabatic energies of the two states (g), and along two new vectors that we describe as the rotated-d and the rotated-g vectors. We show that the dynamics obtained from the d and g prescriptions are significantly different from each other, and we show that the d prescription agrees better with the quantum results. The results of the rotated methods show systematic deviations from the nonrotated results, and in general, the error of the nonrotated methods is smaller. The nonrotated TFS-d method is thus the most accurate method for this system, which was selected for detailed study precisely because it is more sensitive to the choice of hopping vector than previously studied systems.

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Partial widths of feshbach funnel resonances in the Na(3p) � H2 exciplex

Cited by 18 publications

References 33 publications

Evolutionary algorithms and their application to optimal control studies

Evolutionary algorithms and their application to optimal control studies

Introductory lecture: Nonadiabatic effects in chemical dynamics

Quantum Mechanical and Quasiclassical Trajectory Surface Hopping Studies of the Electronically Nonadiabatic Predissociation of the Ã State of NaH₂

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Partial widths of feshbach funnel resonances in the Na(3p) � H2 exciplex

Cited by 18 publications

References 33 publications

Evolutionary algorithms and their application to optimal control studies

Evolutionary algorithms and their application to optimal control studies

Introductory lecture: Nonadiabatic effects in chemical dynamics

Quantum Mechanical and Quasiclassical Trajectory Surface Hopping Studies of the Electronically Nonadiabatic Predissociation of the Ã State of NaH2

Contact Info

Product

Resources

About

Quantum Mechanical and Quasiclassical Trajectory Surface Hopping Studies of the Electronically Nonadiabatic Predissociation of the Ã State of NaH₂