Efficient Semiclassical Dynamics for Vibronic Spectroscopy beyond Harmonic, Condon, and Zero-Temperature Approximations

Begušić, Tomislav; Vaníček, Jiří

doi:10.2533/chimia.2021.261

Cited by 10 publications

(4 citation statements)

References 45 publications

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“…Instead of costly full quantum dynamics, various semiclassical approximations can be used to calculate an absorption spectrum. 21 , 22 Despite being theoretically rigorous, methods based on quantum wavepacket dynamics can be computationally involved and often require approximations such as reducing the dimensionality of the system to a few important normal modes.…”

Section: Introductionmentioning

confidence: 99%

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

Prlj

Marsili

Hutton

et al. 2021

ACS Earth Space Chem.

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Characterizing the photochemical reactivity of transient volatile organic compounds (VOCs) in our atmosphere begins with a proper understanding of their abilities to absorb sunlight. Unfortunately, the photoabsorption cross-sections for a large number of transient VOCs remain unavailable experimentally due to their short lifetime or high reactivity. While structure–activity relationships (SARs) have been successfully employed to estimate the unknown photoabsorption cross-sections of VOCs, computational photochemistry offers another promising strategy to predict not only the vertical electronic transitions of a given molecule but also the width and shape of the bands forming its absorption spectrum. In this work, we focus on the use of the nuclear ensemble approach (NEA) to determine the photoabsorption cross-section of four exemplary VOCs, namely, acrolein, methylhydroperoxide, 2-hydroperoxy-propanal, and (microsolvated) pyruvic acid. More specifically, we analyze the influence that different strategies for sampling the ground-state nuclear density—Wigner sampling and ab initio molecular dynamics with a quantum thermostat—can have on the simulated absorption spectra. We highlight the potential shortcomings of using uncoupled harmonic modes within Wigner sampling of nuclear density to describe flexible or microsolvated VOCs and some limitations of SARs for multichromophoric VOCs. Our results suggest that the NEA could constitute a powerful tool for the atmospheric community to predict the photoabsorption cross-section for transient VOCs.

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Section: Introductionmentioning

confidence: 99%

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

Prlj

Marsili

Hutton

et al. 2021

ACS Earth Space Chem.

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“…As a result, its Gaussian form is conserved; the center of the wavepacket follows a classical trajectory, while its width is adjusted according to the instantaneous Hessian of the potential energy surface (PES). Whereas in the original ab initio TGA − the Hessian of the potential energy is updated over time, in the single-Hessian version, − implemented in TURBOMOLE as part of the module, the Hessian is kept constant throughout the dynamics. Therefore, the overall additional cost compared to the conventional harmonic approximation is that of a single ab initio trajectory in the final electronic state, which is simulated using the module.…”

Section: Recent Developmentsmentioning

confidence: 99%

TURBOMOLE: Today and Tomorrow

Franzke

Holzer

Andersen

et al. 2023

J. Chem. Theory Comput.

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TURBOMOLE is a highly optimized software suite for largescale quantum-chemical and materials science simulations of molecules, clusters, extended systems, and periodic solids. TURBOMOLE uses Gaussian basis sets and has been designed with robust and fast quantum-chemical applications in mind, ranging from homogeneous and heterogeneous catalysis to inorganic and organic chemistry and various types of spectroscopy, light− matter interactions, and biochemistry. This Perspective briefly surveys TURBOMOLE's functionality and highlights recent developments that have taken place between 2020 and 2023, comprising new electronic structure methods for molecules and solids, previously unavailable molecular properties, embedding, and molecular dynamics approaches. Select features under development are reviewed to illustrate the continuous growth of the program suite, including nuclear electronic orbital methods, Hartree−Fock-based adiabatic connection models, simplified time-dependent density functional theory, relativistic effects and magnetic properties, and multiscale modeling of optical properties.

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“…Γ( t ) is the dephasing term in its more general form; for example, Γ( t ) = e – γt corresponds to the Lorentzian line shape in the KHD expression (eq ). In other words, the computation of C ( t ) requires the time propagation of a quantum wavepacket false| ψ ( t ) false⟩ = exp ( − i Ĥ e t / ℏ ) false| ψ 0 ( ν̅ ) false⟩ in the excited electronic state, which is computationally costly for molecular Raman probes with a typical size of 50–100 atoms, even with, for example, trajectory-guided Gaussian wavepacket approaches. − In fact, the number of ab initio computations in the excited electronic state should be minimized to allow for efficient analysis of relatively large molecules.…”

Section: Theorymentioning

confidence: 99%

Computational Design of Molecular Probes for Electronic Preresonance Raman Scattering Microscopy

Tao

Begušić

et al. 2023

J. Phys. Chem. B

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Recently developed electronic preresonance stimulated Raman scattering (epr-SRS) microscopy, in which the Raman signal of a dye is significantly boosted by setting the incident laser frequency near the electronic excitation energy, has pushed the sensitivity of SRS microscopy close to that offered by confocal fluorescence microscopy. Prominently, the maintained narrow line-width of epr-SRS also offers high multiplexity that breaks the “color barrier” in optical microscopy. However, detailed understanding of the fundamental mechanism in these epr-SRS dyes still remains elusive. Here, we combine experiments with theoretical modeling to investigate the structure–function relationship, aiming to facilitate the design of new probes and expanding epr-SRS palettes. Our ab initio approach employing the displaced harmonic oscillator (DHO) model provides a consistent agreement between simulated and experimental SRS intensities of various triple-bond bearing epr-SRS probes with distinct scaffolds. We further review two popular approximate expressions for epr-SRS, namely the short-time and Albrecht A-term equations, and compare them to the DHO model. Overall, the theory allows us to illustrate how the observed intensity differences between molecular scaffolds stem from the coupling strength between the electronic excitation and the targeted vibrational mode, leading to a general design strategy for highly sensitive next-generation vibrational imaging probes.

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Efficient Semiclassical Dynamics for Vibronic Spectroscopy beyond Harmonic, Condon, and Zero-Temperature Approximations

Cited by 10 publications

References 45 publications

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

Calculating Photoabsorption Cross-Sections for Atmospheric Volatile Organic Compounds

TURBOMOLE: Today and Tomorrow

Computational Design of Molecular Probes for Electronic Preresonance Raman Scattering Microscopy

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