Direct Observation of Disrotatory Ring-Opening in Photoexcited Cyclobutene Using ab Initio Molecular Dynamics

and, M. Ben-Nun‡; Martı́nez, Todd J.

doi:10.1021/ja9943896

Cited by 24 publications

(15 citation statements)

References 26 publications

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“…202 An alternative to MS-CASPT2 is Multi-Reference Configuration Interaction (MRCI), which also benefits from efficient implementations of analytical gradients and nonadiabatic coupling vectors. [209][210] MRCIS and MRCISD have been extensively used in combination with trajectory surface hopping 102,[211][212] and with AIMS dynamics, 46,143,[213][214] but its computational cost limits the size of the molecules that can be simulated. The extended multistate complete active space second-order perturbation theory (XMS-CASPT2), [215][216] which offers a more robust description of conical intersections than MS-CASPT2, 217 has recently been used in combination with TSH.…”

Section: Aims Review -Page 48mentioning

confidence: 99%

Ab Initio Nonadiabatic Quantum Molecular Dynamics

2018

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The Born-Oppenheimer approximation underlies much of chemical simulation and provides the framework defining the potential energy surfaces that are used for much of our pictorial understanding of chemical phenomena. However, this approximation breaks down when the dynamics of molecules in excited electronic states are considered. Describing dynamics when the Born-Oppenheimer approximation breaks down requires a quantum mechanical description of the nuclei. Chemical reaction dynamics on excited electronic states is critical for many applications in renewable energy, chemical synthesis, and bioimaging. Furthermore, it is necessary in order to connect with many ultrafast pump-probe spectroscopic experiments. In this review, we provide an overview of methods that can describe nonadiabatic dynamics, with emphasis on those that are able to simultaneously address the quantum mechanics of both electrons and nuclei. Such ab initio quantum molecular dynamics methods solve the electronic Schrödinger equation alongside the nuclear dynamics and thereby avoid the need for precalculation of potential energy surfaces and nonadiabatic coupling matrix elements. Two main families of methods are commonly employed to simulate nonadiabatic dynamics in molecules: full quantum dynamics, such as the multiconfigurational time-dependent Hartree method, and classical trajectory-based approaches, such as trajectory surface hopping. In this review, we describe a third class of methods that is intermediate between the two: Gaussian basis set expansions built around trajectories.

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Section: Aims Review -Page 48mentioning

confidence: 99%

Ab Initio Nonadiabatic Quantum Molecular Dynamics

2018

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“…20,23,27,[57][58][59] In this regard it is very encouraging that even the results from the most approximate FMS method, i.e., FMS-M, are at least as good as and sometimes better than the remarkably robust TSH scheme without suf-fering from the latter's undesirable feature of discontinuous surface switches. It has been previously demonstrated that variants of FMS that are even more approximate than FMS-M, such as the multiple independent spawning method, alleviate some well-known problems in TSH methods, 17 e.g., the incorrect treatment of phase coherence that has been previously discussed in the literature.…”

Section: Possible Improvementsmentioning

confidence: 99%

Comparison of full multiple spawning, trajectory surface hopping, and converged quantum mechanics for electronically nonadiabatic dynamics

Hack¹,

Wensmann²,

Truhlar³

et al. 2001

The Journal of Chemical Physics

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147

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Time-dependent quantum wave packet dynamics of the C + OH reaction on the excited electronic state J. Chem. Phys. 138, 094318 (2013); 10.1063/1.4793395 Dynamics of the O ( P 3 ) + H 2 reaction at low temperatures: Comparison of quasiclassical trajectory with quantum scattering calculations Quantum reactive scattering in three dimensions using adiabatically adjusting principal axis hyperspherical coordinates: Periodic distributed approximating functional method for surface functionsWe present calculations employing the simplest version of the full multiple spawning method, FMS-M or minimal FMS, for electronically nonadiabatic quantum dynamics using three model potential energy matrices with different strengths and ranges for the diabatic coupling. We first demonstrate stability of the branching probabilities and final energy distributions with respect to the parameters in the FMS-M method. We then compare the method to a variety of other semiclassical methods, as well as to accurate quantum mechanical results for three-dimensional atom-diatom reactions and quenching processes; the deviations of the semiclassical results from the accurate quantum mechanical ones are averaged over nine cases. In the adiabatic electronic representation, the FMS-M method provides some improvement over Tully's fewest switches trajectory surface hopping method. However, both methods, irrespective of electronic representation, systematically overpredict the extent of reaction in comparison to the exact quantum mechanical results. The present work provides a baseline for understanding the simplest member of the hierarchy of FMS methods and its relationship to established surface hopping methods.

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“…Interestingly, the limited subset of 20 trajectories is sufficient to capture the evolution of the dynamics qualitatively. In part, this reflects that the diffraction signal is dominated by the comparatively simple dynamics of the C-C bond [75], which is well reproduced by the smaller subset of trajectories, but the observation is more general since we know from earlier studies that a small number of trajectories can do a good job of capturing the essence of a reaction path [79]. This observation is also commensurate with recent work on the ring-opening reaction of CHD, which found that the time-dependent diffraction pattern for the reaction could be reproduced accurately by a comparatively small number of trajectories representative of the dynamics [6].…”

Section: Ethylenementioning

confidence: 87%

Fundamental Limits on Spatial Resolution in Ultrafast X-ray Diffraction

Kirrander

Weber

2017

Applied Sciences

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X-ray Free-Electron Lasers have made it possible to record time-sequences of diffraction images to determine changes in molecular geometry during ultrafast photochemical processes. Using state-of-the-art simulations in three molecules (deuterium, ethylene, and 1,3-cyclohexadiene), we demonstrate that the nature of the nuclear wavepacket initially prepared by the pump laser, and its subsequent dispersion as it propagates along the reaction path, limits the spatial resolution attainable in a structural dynamics experiment. The delocalization of the wavepacket leads to a pronounced damping of the diffraction signal at large values of the momentum transfer vector q, an observation supported by a simple analytical model. This suggests that high-q measurements, beyond 10-15 Å −1 , provide scant experimental payback, and that it may be advantageous to prioritize the signal-to-noise ratio and the time-resolution of the experiment as determined by parameters such as the repetition-rate, the photon flux, and the pulse durations. We expect these considerations to influence future experimental designs, including source development and detection schemes.

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Direct Observation of Disrotatory Ring-Opening in Photoexcited Cyclobutene Using ab Initio Molecular Dynamics

Cited by 24 publications

References 26 publications

Ab Initio Nonadiabatic Quantum Molecular Dynamics

Ab Initio Nonadiabatic Quantum Molecular Dynamics

Comparison of full multiple spawning, trajectory surface hopping, and converged quantum mechanics for electronically nonadiabatic dynamics

Fundamental Limits on Spatial Resolution in Ultrafast X-ray Diffraction

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