The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Gregory K. Schenter - One of the best experts on this subject based on the ideXlab platform.
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The reactive flux method in the energy diffusion regime. II. Importance of the solvent’s spectral profile
The Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the ov...
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the reactive flux method in the energy diffusion regime ii importance of the solvent s spectral profile
Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the ov...
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The reactive flux method in the energy diffusion regime. II. Importance of the solvent’s spectral profile
The Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the overall rate. As predicted in paper I [S. C. Tucker, J. Chem. Phys. 101, 2006 (1994)], the reactive flux in this Case has two plateaus corresponding to two phenomenological rate constants. Mean first passage time calculations confirm that only the first of these two plateaus—which corresponds to the PGH estimate of the rate constant—is observed in the reactive flux simulations.
Sabine K. Reese - One of the best experts on this subject based on the ideXlab platform.
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The reactive flux method in the energy diffusion regime. II. Importance of the solvent’s spectral profile
The Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the ov...
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the reactive flux method in the energy diffusion regime ii importance of the solvent s spectral profile
Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the ov...
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The reactive flux method in the energy diffusion regime. II. Importance of the solvent’s spectral profile
The Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the overall rate. As predicted in paper I [S. C. Tucker, J. Chem. Phys. 101, 2006 (1994)], the reactive flux in this Case has two plateaus corresponding to two phenomenological rate constants. Mean first passage time calculations confirm that only the first of these two plateaus—which corresponds to the PGH estimate of the rate constant—is observed in the reactive flux simulations.
Susan C. Tucker - One of the best experts on this subject based on the ideXlab platform.
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The reactive flux method in the energy diffusion regime. II. Importance of the solvent’s spectral profile
The Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the ov...
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the reactive flux method in the energy diffusion regime ii importance of the solvent s spectral profile
Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the ov...
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The reactive flux method in the energy diffusion regime. II. Importance of the solvent’s spectral profile
The Journal of Chemical Physics, 1995Co-Authors: Sabine K. Reese, Susan C. Tucker, Gregory K. SchenterAbstract:The dependence of energy‐diffusion‐limited unimolecular‐rate constants upon the form of the solvent’s spectral profile is studied using generalized Langevin equation (GLE) dynamics. We find that the initial energy relaxation of the solute as it leaves the barrier region and the subsequent vibrational relaxation into the solute reactant well are governed by different frequency regions of the solvent’s spectral profile. Additionally, we find that for the Case of a slowly relaxing bath the rate can depend quite dramatically upon the form of the Friction kernel used in the GLE. Specifically, while the initial solute energy relaxation is observed to be similar for the Gaussian and exponential Friction Cases studied, there is a bottleneck to solute vibrational energy relaxation in the Gaussian Friction Case that is not present in the exponential Friction Case. In the Gaussian Friction Case, we find that neither the reactive flux method nor the Pollak–Grabert–Hanggi turnover theory (PGH) correctly predict the overall rate. As predicted in paper I [S. C. Tucker, J. Chem. Phys. 101, 2006 (1994)], the reactive flux in this Case has two plateaus corresponding to two phenomenological rate constants. Mean first passage time calculations confirm that only the first of these two plateaus—which corresponds to the PGH estimate of the rate constant—is observed in the reactive flux simulations.
Christophe Voisin - One of the best experts on this subject based on the ideXlab platform.
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Dynamic triggering of earthquakes: The nonlinear slip‐dependent Friction Case
Journal of Geophysical Research: Solid Earth, 2002Co-Authors: Christophe VoisinAbstract:[1] The problem of earthquake triggering by dynamic stress waves is studied. A finite fault of length L embedded in an elastic space is considered. The prescribed nonlinear slip-dependent Friction law is characterized by a nonconstant weakening rate α. The fault is perturbed by a sinusoidal stress wave of wavelength λ and amplitude a. As a general result, it is shown that for a given fault and a given Friction law, low frequencies are more likely to trigger the rupture than high frequencies. In addition, the occurrence of triggering depends on the balance between intrinsic fault mechanics and the loading parameters. Two behaviors are possible depending on the Friction law: some faults exhibit a threshold in frequency to be triggered, while other faults exhibit a threshold in amplitude. These two qualitative behaviors may be explained by considering the nondimensional weakening rate β = α × L/2 and β0 the universal constant of stability computed by Dascalu et al. [2000]. The faults that present a threshold in frequency are intrinsically unstable: their initial nondimensional weakening rate β(0) exceeds β0. On the contrary, the faults that present a threshold in amplitude are intrinsically stable, i.e., initially β(0) < β0. Because of the nonlinearity of the Friction law, there is a characteristic slip uc for which β(uc) ≥ β0. For a sufficiently large amplitude the fault may then experience a stability/instability transition. These results are independent of the shape of the perturbation and also hold for a static stress increase.
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Dynamic triggering of earthquakes: the nonlinear slip-dependent Friction Case.
Journal of Geophysical Research : Solid Earth, 2002Co-Authors: Christophe VoisinAbstract:The problem of earthquake triggering by dynamic stress waves is studied. A finite fault of length L embedded in an elastic space is considered. The prescribed nonlinear slip‐dependent Friction law is characterized by a nonconstant weakening rate α. The fault is perturbed by a sinusoidal stress wave of wavelength λ and amplitude a. As a general result, it is shown that for a given fault and a given Friction law, low frequencies are more likely to trigger the rupture than high frequencies. In addition, the occurrence of triggering depends on the balance between intrinsic fault mechanics and the loading parameters. Two behaviors are possible depending on the Friction law: some faults exhibit a threshold in frequency to be triggered, while other faults exhibit a threshold in amplitude. These two qualitative behaviors may be explained by considering the nondimensional weakening rate β = α × L/2 and β0 the universal constant of stability computed by Dascalu et al. [2000]. The faults that present a threshold in frequency are intrinsically unstable: their initial nondimensional weakening rate β(0) exceeds β0. On the contrary, the faults that present a threshold in amplitude are intrinsically stable, i.e., initially β(0) < β0. Because of the nonlinearity of the Friction law, there is a characteristic slip uc for which β(uc) ≥ β0. For a sufficiently large amplitude the fault may then experience a stability/instability transition. These results are independent of the shape of the perturbation and also hold for a static stress increase.
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Dynamic triggering of earthquakes: The linear slip‐dependent Friction Case
Geophysical Research Letters, 2001Co-Authors: Christophe VoisinAbstract:This paper is devoted to the modeling of dynamic triggering of earthquakes by a sinusoidal plane wave. I consider a 2D antiplane finite fault of length L under a linear slip‐dependent Friction law, characterized by a nondimensional weakening parameter β. The finite fault is perturbed by an incident sinusoidal stress wave of wavelength λ and amplitude a. The positive pulse of the wave loads the fault and promotes the instability, while the negative pulse tends to heal the initiation process that may lead to the rupture. The occurrence of triggering depends on the balance between the loading terms and the intrinsic mechanics of the fault. Both amplitude and frequency exert a clock advance effect on the triggering. A threshold in frequency for the incident wave to trigger the rupture is revealed, which depends on the non‐dimensional weakening parameter β and separates a nontriggering domain with stable slip from a triggering domain with unstable slip.
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Dynamic triggering of earthquakes: the linear slip-dependent Friction Case
Geophysical Research Letters, 2001Co-Authors: Christophe VoisinAbstract:This paper is devoted to the modeling of dynamic triggering of earthquakes by a sinusoidal plane wave. I consider a 2D antiplane finite fault of length L under a linear slip‐dependent Friction law, characterized by a nondimensional weakening parameter β. The finite fault is perturbed by an incident sinusoidal stress wave of wavelength λ and amplitude a. The positive pulse of the wave loads the fault and promotes the instability, while the negative pulse tends to heal the initiation process that may lead to the rupture. The occurrence of triggering depends on the balance between the loading terms and the intrinsic mechanics of the fault. Both amplitude and frequency exert a clock advance effect on the triggering. A threshold in frequency for the incident wave to trigger the rupture is revealed, which depends on the non‐dimensional weakening parameter β and separates a nontriggering domain with stable slip from a triggering domain with unstable slip.
Paul A Shade - One of the best experts on this subject based on the ideXlab platform.
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a combined experimental and simulation study to examine lateral constraint effects on microcompression of single slip oriented single crystals
Acta Materialia, 2009Co-Authors: Michael D Uchic, D M Dimiduk, Paul A Shade, R Wheeler, Yoon Suk Choi, H L FraserAbstract:A custom in situ scanning electron microscopy mechanical testing system has been used to study the compressive deformation behavior of single-slip oriented Rene N5 single-crystal Ni superalloy microcrystals. Two different compression platens were used to explore the effect of lateral stiffness on the resultant mechanical response, which approximated either a high-Friction or effectively zero-Friction Case. The change in the lateral constraint of the test system had a demonstrable effect on many aspects or attributes of plastic flow: the yield stress and strain-hardening behavior, the intermittency of strain bursts, the spatial distribution of slip bands, and the development of internal crystal rotations. Finite-element modeling of the microcompression experiments using an anisotropic crystal plasticity framework provided insight regarding changes in the internal stress field and resultant activity of slip systems. The experimental findings are rationalized based on these simulation results.
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a combined experimental and computational study to examine lateral constraint effects on single slip oriented microcompression experiments preprint
2009Co-Authors: Michael D Uchic, D M Dimiduk, H L Fraser, Paul A Shade, R Wheeler, Yoon Suk ChoiAbstract:Abstract : A custom in-situ SEM mechanical testing system has been used to study the compressive deformation behavior of single-slip oriented Rene N5 microcrystals. Two different compression platens were used to explore the effect of lateral stiffness on the resultant mechanical response, which approximated either a full-Frictional or zero-Friction Case. The change in the lateral constraint of the test system had a demonstrable effect on many aspects or attributes of plastic flow: the measured modulus, yield stress and strain hardening behavior, the intermittency of strain bursts, the spatial distribution of slip bands, and the development of internal lattice rotations. Finite element modeling of the microcompression experiments using a crystal plasticity framework enabled insight regarding changes in the internal stress field and resultant slip system activity. The experimental tests findings are rationalized based on these simulation results.
