Computing vibrational energy relaxation for high-frequency modes in condensed environments

Rostkier‐Edelstein, Dorita; Gräf, Peter; Nitzan, Abraham

doi:10.1063/1.475323

Cited by 56 publications

(29 citation statements)

References 31 publications

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“…As a result, it becomes increasingly more difficult to average out the statistical noise accompanying any real-life simulation that is needed in order to calculate the increasingly small value of C̃ s (ω) at high frequencies. The results reported below were obtained by following the common practice of obtaining C̃ s (ω) at high frequencies by extrapolating the exponential gap law, which emerged at significantly lower frequencies. − It should be noted that, strictly speaking, the exponential gap law has only been rigorously derived in the case of exponential repulsion interaction . However, it was observed to be valid for the system under discussion in this paper.…”

Section: Model Parameters and Simulation Techniquesmentioning

confidence: 90%

Vibrational Energy Relaxation in Liquid HCl and DCl via the Linearized Semiclassical Method: Electrostriction versus Quantum Delocalization

2011

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The rate constant for vibrational energy relaxation of the H-Cl stretch in liquid HCl (T = 188K, ρ = 19.671 nm(-3)) is calculated within the framework of the Landau-Teller formula. The force-force correlation function is calculated via the recently introduced force-derivative-free linearized semiclassical method [Vázquez et al. J. Phys. Chem. A2010, 114, 5682]. The calculated vibrational energy relaxation rate constant is found to be in excellent agreement with experiment, and the electrostatic force is found to contribute significantly to the high frequency component of the force-force correlation function. In contrast, the corresponding classical vibrational energy relaxation rate constant is found to be 2 orders of magnitude slower than the experimental value, and the classical force-force correlation function is found to be dominated by the Lennard-Jones forces. These observations suggest that quantum delocalization, enhanced by the light mass of hydrogen, amplifies the contribution of repulsive Coulombic forces to the force-force correlation function, thereby making electrostriction an unlikely mechanism for vibrational energy relaxation in the case of hydrogen stretches. This interpretation is reinforced by the results of a similar calculation in the case of the D-Cl stretch in liquid DCl under the same conditions. In this case, the quantum enhancement of the vibrational energy relaxation rate constant is observed to be greatly diminished in comparison to HCl, thereby giving rise to a reversal of the isotope effect in comparison to that predicted by the corresponding classical treatment (i.e., whereas the classical vibrational energy relaxation rate of DCl is faster than that of HCl, the opposite trend is predicted by the linearized semiclassical treatment). It is also shown that the vibrational energy relaxation of DCl is completely dominated by the Lennard-Jones forces within either classical and semiclassical treatments, thereby suggesting that electrostriction is the underlying mechanism in this case.

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Section: Model Parameters and Simulation Techniquesmentioning

confidence: 90%

Vibrational Energy Relaxation in Liquid HCl and DCl via the Linearized Semiclassical Method: Electrostriction versus Quantum Delocalization

2011

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“…It is widely accepted that the excess vibrational energy either is transferable to the solvent bath modes or participates in a resonant transfer to solvent vibrations with similar vibrational frequencies. , Also called friction spectra, the spectral distribution of the bath modes of solvent is continuous and highly dense, which plays a major role in the vibrational cooling in most cases. − For polyatomic molecules, an increased rate of vibrational relaxation in protic solvents has been reported by several groups. Vibrational relaxation of betaine 30 in the ground state is increased in a protic solvent, with a linear correlation between the rates and several vibrational modes through IVR; the rate of IVR varies with the molar number of OH groups per unit volume of solvent .…”

Section: Discussionmentioning

confidence: 99%

Dynamics of the Excited States of p-Terphenyl and Tetracene: Solute–Solvent Interaction

et al. 2011

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The time-resolved fluorescence of p-terphenyl, 2,2″-dimethyl-p-terphenyl (dm-terphenyl), and tetracene dissolved in solvents was measured with fluorescence up-conversion and time-correlated single-photon counting. We characterized the relaxation dynamics of vibrational energy in these three molecules by examining their properties in solvents of varied physical properties. According to the measured curves of fluorescence decays obtained at excitation wavelength 266/256 nm, we propose that p-terphenyl and dm-terphenyl both undergo initially an ultrafast intramolecular redistribution of vibrational energy. A conformational relaxation of p-terphenyl in excited-state S 1 with time constant 6–13 ps is proposed from its linear dependence on the viscosity of solvents. This process and vibrational energy relaxation are accelerated in a protic solvent involving efficient coupling to the high-energy bath modes of the solvent. Because the torsional conformational change of dm-terphenyl is effectively inhibited by the steric hindrance imposed by its methyl substituents, its vibrational relaxation is found to be independent of the viscosity of the solvent but remains rapid with time constant 5.2–8.8 ps. The time constant of vibrational relaxation in tetracene is observed to be 12–16 ps, with no evident dependence on solvent viscosity or thermal diffusivity. The fact that accepting modes with greater energy are more effective in transferring energy for a system with a large excess of vibrational energy is proposed to explain the ratio of the rates of vibrational relaxation for methanol MeOH/MeOD ≈ 2.

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“…More generally, however, we usually assume that the system is harmonic, but the bath is anharmonic and the coupling need not be linear. In such a case, there is also a long-standing literature for evaluating FGR rates approximately with classical mechanics. − The inevitable question that arises is how to choose the appropriate QCF . Estimates based on different choices of QCF can vary by several orders of magnitude. ,− Alternatively, Geva et al have developed a semiclassical method to compute the quantum time correlation function. ,− …”

Section: Simulation Detailsmentioning

confidence: 99%

Vibrational Energy Relaxation: A Benchmark for Mixed Quantum–Classical Methods

Jain

Subotnik

2017

J. Phys. Chem. A

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We investigate the ability of mixed quantum-classical methods to capture the dynamics of vibrational energy relaxation. Several methods, including surface hopping, and Ehrenfest and symmetrical quasiclassical (SQC) dynamics, are benchmarked for the exactly solvable model problem of a harmonic oscillator bilinearly coupled to a bath of harmonic oscillators. Results show that, very often, one can recover accurate vibrational relaxation rates and detailed balance using simple mixed quantum-classical approaches. A few anomalous results do appear, however, especially regarding Ehrenfest and SQC dynamics.

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Computing vibrational energy relaxation for high-frequency modes in condensed environments

Cited by 56 publications

References 31 publications

Vibrational Energy Relaxation in Liquid HCl and DCl via the Linearized Semiclassical Method: Electrostriction versus Quantum Delocalization

Vibrational Energy Relaxation in Liquid HCl and DCl via the Linearized Semiclassical Method: Electrostriction versus Quantum Delocalization

Dynamics of the Excited States of p-Terphenyl and Tetracene: Solute–Solvent Interaction

Vibrational Energy Relaxation: A Benchmark for Mixed Quantum–Classical Methods

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