A rate-dependent three-dimensional free energy model for ferroelectric single crystals

AbstractThe paper presents a free energy model for the pseudoelastic behavior of shape memory alloys. It is based on a stochastic homogenization process, which uses distributions in energy barriers and internal stresses to represent effects typically encountered in polycrystalline materials. This concept leads to a realistic desription of the rate-dependent inner loop behavior, but is characterized by rather long computation times. This is prohibitive in regard to a potential implementation into other numerical codes, such as finite element or optimal control programs or a Matlab/Simulink environment. For this purpose a parameterization method is introduced, which is derived from the concept of a representative single crystal. The approach preserves the desirable properties of the original formulation, at the same time reducing the numerical effort significantly. Finally, we show that the method can reproduce the experimentally observed behavior accurately over a large range of strain rates including the minor loop behavior.

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Hydrogen Atom Transfer Reaction Free Energy as a Predictor of Abiotic Nitroaromatic Reduction Rate Constants: A Comprehensive Analysis

10.26434/chemrxiv.8009720.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Dominic Di Toro ◽

Kevin P. Hickey ◽

Herbert E. Allen ◽

Richard F. Carbonaro ◽

Pei C. Chiu

Keyword(s):

Free Energy ◽

Hydrogen Atom ◽

Hydrogen Atom Transfer ◽

Energy Model ◽

Second Order ◽

Transfer Model ◽

Atom Transfer ◽

Order Rate ◽

Linear Free Energy ◽

Free Energy Model

<div>A linear free energy model is presented that predicts the second order rate constant for the abiotic reduction of nitroaromatic compounds (NACs). For this situation previously presented models use the one electron reduction potential of the NAC reaction. If such value is not available, it has been has been proposed that it could be computed directly or estimated from the electron affinity (EA). The model proposed herein uses the Gibbs free energy of the hydrogen atom transfer (HAT) as the parameter in the linear free energy model. Both models employ quantum chemical computations for the required thermodynamic parameters. The available and proposed models are compared using second order rate constants obtained from five investigations reported in the literature in which a variety of NACs were exposed to a variety of reductants. A comprehensive analysis utilizing all the NACs and reductants demonstrate that the computed hydrogen atom transfer model and the experimental one electron reduction potential model have similar root mean square errors and residual error probability distributions. In contrast, the model using the computed electron affinity has a more variable residual error distribution with a significant number of outliers. The results suggest that a linear free energy model utilizing computed hydrogen transfer reaction free energy produces a more reliable prediction of the NAC abiotic reduction second order rate constant than previously available methods. The advantages of the proposed hydrogen atom transfer model and its mechanistic implications are discussed as well.</div>

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Affinity and Specificity of Protein U1A-RNA Complex Formation Based on an Additive Component Free Energy Model

Journal of Molecular Biology ◽

10.1016/j.jmb.2007.06.003 ◽

2007 ◽

Vol 371 (5) ◽

pp. 1405-1419 ◽

Cited By ~ 34

Author(s):

Bethany L. Kormos ◽

Yulia Benitex ◽

Anne M. Baranger ◽

David L. Beveridge

Keyword(s):

Free Energy ◽

Complex Formation ◽

Energy Model ◽

Additive Component ◽

Free Energy Model ◽

Rna Complex

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Predictive in Silico All-Atom Folding of a Four-Helix Protein with a Free-Energy Model

Journal of the American Chemical Society ◽

10.1021/ja0453681 ◽

2004 ◽

Vol 126 (51) ◽

pp. 16736-16737 ◽

Cited By ~ 25

Author(s):

Alexander Schug ◽

Wolfgang Wenzel

Keyword(s):

Free Energy ◽

In Silico ◽

Energy Model ◽

Free Energy Model

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Predictive folding of a β-hairpin protein in an all-atom free-energy model

EPL (Europhysics Letters) ◽

10.1209/epl/i2006-10245-y ◽

2006 ◽

Vol 76 (1) ◽

pp. 156-162 ◽

Cited By ~ 7

Author(s):

W Wenzel

Keyword(s):

Free Energy ◽

Energy Model ◽

Free Energy Model

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A Two-Dimensional Free Energy Model for Single Crystalline Ferroelectrics

MRS Proceedings ◽

10.1557/proc-881-cc1.7 ◽

2005 ◽

Vol 881 ◽

Author(s):

Sang-Joo Kim ◽

Stefan Seelecke ◽

Brian L. Ball ◽

Ralph C. Smith ◽

Chang-Hoan Lee

Keyword(s):

Free Energy ◽

Evolution Equations ◽

Saddle Points ◽

Ferroelectric Materials ◽

Energy Model ◽

Two Dimensions ◽

Two Dimensional ◽

Energy Potential ◽

Single Crystalline ◽

Free Energy Model

AbstractThe one-dimensional free energy model for ferroelectric materials developed in [1-3] is general-ized to two dimensions. The proposed two-dimensional energy potential consists of four energy wells corresponding to four variants of the material, four saddle points representing the barriers for 900 switching processes, and a local energy maximum across which 1800-switching processes take place. The free energy potential is combined with the evolution equations based on the theory of thermally activated processes. The prediction of the model is compared with the recent measurements on a Ba- TiO3 single crystalline ferroelectric in [4]. The responses of the model at various loading frequencies are calculated and the kinetics of 900 and 1800 switching processes are discussed.

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