Photoinduced Dynamics with Constrained Vibrational Motion: FrozeNM Algorithm

Ab initio molecular dynamics (AIMD) simulation, analyzed in terms of vibrational normal modes, is a widely used technique that facilitates understanding of complex structural motions and coupling between electronic and nuclear degrees of freedom. Usually, only a subset of vibrations is directly invo...

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Bibliographic Details
Published in:Journal of chemical theory and computation 2020-12, Vol.16 (12), p.7289-7298
Main Authors: Negrin-Yuvero, H, Freixas, V. M, Rodriguez-Hernandez, B, Rojas-Lorenzo, G, Tretiak, S, Bastida, A, Fernandez-Alberti, S
Format: Article
Language:English
Subjects:
Algorithms
Constraint modelling
Coupling (molecular)
Dynamics
Energy transfer
Excitation
Freezing
Impact analysis
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Material Science
Molecular dynamics
Simulation
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Summary:Ab initio molecular dynamics (AIMD) simulation, analyzed in terms of vibrational normal modes, is a widely used technique that facilitates understanding of complex structural motions and coupling between electronic and nuclear degrees of freedom. Usually, only a subset of vibrations is directly involved in the process of interest. The impact of these vibrations can be evaluated by performing AIMD simulations by selectively freezing certain motions. Herein, we present frozen normal mode (FrozeNM), a new algorithm to apply normal-mode constraints in AIMD simulations, as implemented in the nonadiabatic excited state molecular dynamics code. We further illustrate its capacity by analyzing the impact of normal-mode constraints on the photoinduced energy transfer between polyphenylene ethynylene dendrimer building blocks. Our results show that the electronic relaxation can be significantly slowed down by freezing a well-selected small subset of active normal modes characterized by their contributions in the direction of energy transfer. The application of these constraints reduces the nonadiabatic coupling between electronic excited states during the entire dynamical simulations. Furthermore, we validate reduced dimensionality models by freezing all the vibrations, except a few active modes. Altogether, we consider FrozeNM as a useful tool that can be broadly used to underpin the role of vibrational motion in a studied process and to formulate reduced models that describe essential physical phenomena.
ISSN:1549-9618
1549-9626
DOI:10.1021/acs.jctc.0c00930