Dynamics of Proton Transfer and Vibrational Relaxation in Dilute Hydrofluoric Acid

Joutsuka, Tatsuya; Ando, Koji

doi:10.1021/jp108413p

Cited by 8 publications

(15 citation statements)

References 30 publications

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“…This is relevant, for instance, to the IR-induced proton transfer, in which after the excitation the proton transfer occurs and the proton potential becomes quite anharmonic. [3][4][5]59 Therefore, we investigate the vibrational dynamics induced by a strong pulse. The IR spectra by a strong pulse excitation are shown in Fig.…”

Section: Anharmonicitymentioning

confidence: 99%

“…Vibrational relaxation (VR) plays an essential role in many chemical processes in liquids, and the interpretation of the coherence relaxation (dephasing) and vibrational energy relaxation (VER) 1, 2 is vital to reveal the dynamic mechanisms of proton transfer, [3][4][5] energy transport, 6,7 and other chemical processes. Especially, recent advances in ultrafast spectroscopy have clarified dynamical aspects of VR in liquids.…”

Section: Introductionmentioning

confidence: 99%

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Vibrational spectroscopy and relaxation of an anharmonic oscillator coupled to harmonic bath

Joutsuka

Ando

2011

The Journal of Chemical Physics

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The vibrational spectroscopy and relaxation of an anharmonic oscillator coupled to a harmonic bath are examined to assess the applicability of the time correlation function (TCF), the response function, and the semiclassical frequency modulation (SFM) model to the calculation of infrared (IR) spectra. These three approaches are often used in connection with the molecular dynamics simulations but have not been compared in detail. We also analyze the vibrational energy relaxation (VER), which determines the line shape and is itself a pivotal process in energy transport. The IR spectra and VER are calculated using the generalized Langevin equation (GLE), the Gaussian wavepacket (GWP) method, and the quantum master equation (QME). By calculating the vibrational frequency TCF, a detailed analysis of the frequency fluctuation and correlation time of the model is provided. The peak amplitude and width in the IR spectra calculated by the GLE with the harmonic quantum correction are shown to agree well with those by the QME though the vibrational frequency is generally overestimated. The GWP method improves the peak position by considering the zero-point energy and the anharmonicity although the red-shift slightly overshoots the QME reference. The GWP also yields an extra peak in the higher-frequency region than the fundamental transition arising from the difference frequency of the center and width oscillations of a wavepacket. The SFM approach underestimates the peak amplitude of the IR spectra but well reproduces the peak width. Further, the dependence of the VER rate on the strength of an excitation pulse is discussed.

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Section: Anharmonicitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vibrational spectroscopy and relaxation of an anharmonic oscillator coupled to harmonic bath

Joutsuka

Ando

2011

The Journal of Chemical Physics

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“…To understand H-bond structures accompanying solvent reorganization in PT, which is significant for PTs in aqueous solutions, [18][19][20][21] we adopt another coordination number of O A…”

Section: H-bond Numbermentioning

confidence: 99%

“…Such concerted motions of PT and H-bond rearrangement are in line with the previous theoretical simulations. 5,[18][19][20][21] Afterwards, PT proceeds mainly from (n H , n HB ) ∼ (1.8, 3. to obtain another H bond. Also in this jump, there seems to be a small barrier along the n HB coordinate if n H was constrained, yet this barrier can be circumvented by changing n H .…”

Section: H-bond Structurementioning

confidence: 99%

Molecular Mechanism of Autodissociation in Liquid Water: Density Functional Theory Molecular Dynamics Simulations

Joutsuka

2022

Preprint

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Autodissociation in liquid water is one of the most important processes in various topics of physical chemistry, such as acid-base chemistry. Molecular simulations have elucidated most of the molecular mechanisms at the atomic level, yet quantitative analysis to compare with experiments using the potential of mean force (PMF) remains a hurdle, including the definition of reaction coordinates and accuracy of liquid structures by ab initio molecular dynamics (AIMD) simulations with density functional theory (DFT) methods. Here, we perform AIMD simulations with the revPBE-D3 exchange-correlation functional to compute the PMF profiles of autoionization, or proton transfer (PT), in liquid water. For the quantitative analysis with physically meaningful reaction coordinates, we employ a PT coordinate, donor-acceptor (OH--H3O+) distance, and hydrogen (H)-bond number. The one-dimensional (1D) PMF profile along the PT coordinate shows no local minimum in the product state of PT (OH- and H3O+), which is necessary to accurately compute acid dissociation constant (or pKa). On the other hand, the 2D PMF profiles along the PT coordinate and donor-acceptor distance show local minima in the product state and reaction barriers, and the computed pKw is comparable to the experiment. In addition, the 2D PMF profiles along the PT coordinate and the H-bond number reveal the molecular mechanism of the H-bond rearrangement concomitant with PT, in which the H-bond breaking before PT is slightly preferable. These findings indicate that accurate evaluation of pKa by MD simulations requires the donor-acceptor distance in addition to the conventional PT coordinate.

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“…Among them, the solvent reorganization energy in the ET reactions and the spectral shifts is a key quantity that has attracted most attention. Moreover, nonequilibrium solvation problem also exists in some other processes such as proton transfer …”

Section: Introductionmentioning

confidence: 99%

An overview of continuum models for nonequilibrium solvation: Popular theories and new challenge

2015

Int J of Quantum Chemistry

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The effect of solvent on the electron transfer (ET) and spectral shifts has been the focus of experimental and theoretical studies and a key quantity in these studies is the solvent reorganization energy. There are a number of theoretical models toward the evaluation of nonequilibrium solvation free energy that were proposed decades ago and have been applied widely. In the past decade, however, we revisited the original theoretical derivations and identified a serious defect in the popular nonequilibrium solvation models which causes the significant overestimation of solvent reorganization energy and hence predicts a much lowed rate constant for ET in some cases. A rigorous derivation by means of contrained equilibrium principle of thermodynamics was subsequently conducted for the study of nonequilibrium solvation. In this review, the author outlined the intimate interplays among the representative models and analyzed what the possible problem could be. The key idea presented in our recent papers was highlighted. The constrained equilibrium principle in classical thermodynamics and its application to the nonequilibrium solvation were detailed, and a few argumentative examples in literature were taken for the validation of our theory.

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Dynamics of Proton Transfer and Vibrational Relaxation in Dilute Hydrofluoric Acid

Cited by 8 publications

References 30 publications

Vibrational spectroscopy and relaxation of an anharmonic oscillator coupled to harmonic bath

Vibrational spectroscopy and relaxation of an anharmonic oscillator coupled to harmonic bath

Molecular Mechanism of Autodissociation in Liquid Water: Density Functional Theory Molecular Dynamics Simulations

An overview of continuum models for nonequilibrium solvation: Popular theories and new challenge

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