Ab Initio Multiple Spawning Dynamics Using Multi-State Second-Order Perturbation Theory

Tao, Hairong; Levine, Bernard B.; Martı́nez, Todd J.

doi:10.1021/jp9063565

Cited by 149 publications

(181 citation statements)

References 49 publications

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“…The directions that define the branching space for intersections involving a hydrogen bridge across the double bond are presented in Figure 2b. While the gand h-directions for CHE and CHD are completely analogous, they are quite different from the [ 26 further evidence that both of these molecules would be expected to undergo similar excitedstate dynamical processes.…”

Section: Resultsmentioning

confidence: 89%

“…The [1,2] H-shift and [1,2] H-bridge intersections in CHE and CHD correspond to the previously discussed ethylidene-like and H-bridged intersections, respectively. 21,22,25,26,53 Likewise, in closed-ring systems, twistedpyramidalized geometries may involve the breaking of the adjacent CÀC bonds, as seen in the α-and β-cleavage processes for CHE and the single-bond breaking path in CHD. Obviously, there is no clear analogue to the [1,3] H-migration pathway observed in ethylene; however, the efficacy of this intersection type is likely highly dependent both on the twist-pyramidalization displacements required to promote hydrogen bond cleavage and migration, as well as on the ring structure that provides an initial conformationally locked geometry.…”

Section: Resultsmentioning

confidence: 99%

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Through-Bond Interactions and the Localization of Excited-State Dynamics

et al. 2011

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The influence of through-bond interactions on nonadiabatic excited-state dynamics is investigated by time-resolved photoelectron spectroscopy (TRPES) and ab initio computation. We compare the dynamics of cyclohexa-1,4-diene, which exhibits a through-bond interaction known as homoconjugation (the electronic correlation between nonconjugated double bonds), with the nonconjugated cyclohexene. Each molecule was initially excited to a 3s Rydberg state using a 200 nm femtosecond pump pulse. The TRPES spectra of these molecules display similar structure and time constants on a subpicosecond time scale. Our ab initio calculations show that similar sets of conical intersections (a [1,2]- and [1,3]-hydrogen shift, as well as carbon–carbon bond cleavage) are energetically accessible to both molecules and that the geometry and orbital composition at the minimum energy crossing points to the ground state are directly analogous. These experimental and computational results suggest that the excited-state dynamics of cyclohexa-1,4-diene become localized at a single double bond and that the effects of through-bond interaction, dominant in the absorption spectrum, are absent in the excited-state dynamics. The notion of excited-state dynamics being localized at specific sites within the nuclear framework is analogous to the localization of light absorption by a subsystem within the molecule, designated a chromophore. We propose the utility of the analogous concept, denoted here as a dynamophore.

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Through-Bond Interactions and the Localization of Excited-State Dynamics

et al. 2011

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“…As ethylene is the simplest molecule with a C=C double bond, it has been extensively studied both experimentally and computationally. 22,[50][51][52][53][54][55][56][57][58] The AIMC and AIMS simulations were carried out with a modified version of AIMS-MOLPRO, 36 which was extended to include Ehrenfest dynamics for the TBFs. Electronic structure calculations were performed with the CASSCF method using an active space of two electrons in two orbitals and equally weighted stateaveraging over the three lowest singlet states, i.e., SA-3-CAS(2/2).…”

Section: Computational Details and Resultsmentioning

confidence: 99%

“…[49][50][51] With the above prescribed equations for the evolution of the phase and Ehrenfest amplitudes, we can now obtain the equations of motion for the TBF amplitudes c n by inserting the ansatz into the time-dependent Schrödinger equation, giving…”

Section: A Working Equationsmentioning

confidence: 99%

Ab initio multiple cloning algorithm for quantum nonadiabatic molecular dynamics

Makhov

Glover

Martı́nez

et al. 2014

The Journal of Chemical Physics

206

245

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An atomic orbital-based formulation of analytical gradients and nonadiabatic coupling vector elements for the state-averaged complete active space self-consistent field method on graphical processing units We present a new algorithm for ab initio quantum nonadiabatic molecular dynamics that combines the best features of ab initio Multiple Spawning (AIMS) and Multiconfigurational Ehrenfest (MCE) methods. In this new method, ab initio multiple cloning (AIMC), the individual trajectory basis functions (TBFs) follow Ehrenfest equations of motion (as in MCE). However, the basis set is expanded (as in AIMS) when these TBFs become sufficiently mixed, preventing prolonged evolution on an averaged potential energy surface. We refer to the expansion of the basis set as "cloning," in analogy to the "spawning" procedure in AIMS. This synthesis of AIMS and MCE allows us to leverage the benefits of mean-field evolution during periods of strong nonadiabatic coupling while simultaneously avoiding mean-field artifacts in Ehrenfest dynamics. We explore the use of time-displaced basis sets, "trains," as a means of expanding the basis set for little cost. We also introduce a new bra-ket averaged Taylor expansion (BAT) to approximate the necessary potential energy and nonadiabatic coupling matrix elements. The BAT approximation avoids the necessity of computing electronic structure information at intermediate points between TBFs, as is usually done in saddle-point approximations used in AIMS. The efficiency of AIMC is demonstrated on the nonradiative decay of the first excited state of ethylene. The AIMC method has been implemented within the AIMS-MOLPRO package, which was extended to include Ehrenfest basis functions.

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“…In AIMS, this flexibility is attained by adaptively increasing the number of TBFs, in a process called spawning, when the coupling of two states rises above a predefined threshold. As discussed in detail previously, 15,31,34 the nonadiabatic coupling vectors are used in AIMS in three ways: (1) to construct the Hamiltonian matrix elements in eq 5, (2) to decide when spawning occurs, and (3) to determine the momentum of the newly created child TBF's following spawning. In the first two uses, one does not need the entire nonadiabatic coupling vector but rather only the dot product with a (complex) off-diagonal matrix element of the momentum operator.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Role of Rydberg States in the Photochemical Dynamics of Ethylene

et al. 2012

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Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1021/jp2097185Access and use of this website and the material on it are subject to the Terms and Conditions set forth atThe role of Rydberg states in the photochemical dynamics of ethylene Mori, Toshifumi; Glover, William J.; Schuurman, Michael S.; Martinez, Todd J.http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/droits L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site

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Ab Initio Multiple Spawning Dynamics Using Multi-State Second-Order Perturbation Theory

Cited by 149 publications

References 49 publications

Through-Bond Interactions and the Localization of Excited-State Dynamics

Through-Bond Interactions and the Localization of Excited-State Dynamics

Ab initio multiple cloning algorithm for quantum nonadiabatic molecular dynamics

Role of Rydberg States in the Photochemical Dynamics of Ethylene

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