The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
T A Arias - One of the best experts on this subject based on the ideXlab platform.
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uid response in Joint Density-functional theory studies of battery systems
2020Co-Authors: Deniz Gunceler, Kathleen A Schwarz, Kendra Letchworth-weaver, T A AriasAbstract:Delivering the full benets of rst principles calculations to battery materials demands the development of accurate and computationally-ecient electronic structure methods that incorporate the eects of the electrolyte environment and electrode potential. Realistic electrochemical interfaces containing polar surfaces are beyond the regime of validity of existing continuum solvation theories developed for molecules, due to the presence of signicantly stronger electric elds. We present an ab initio theory of the nonlinear dielectric and ionic response of solvent environments within the framework of Joint Density- functional theory, with precisely the same optimizable parameters as conventional polarizable continuum models. We demonstrate that the resulting nonlinear theory agrees with the standard linear models for organic molecules and metallic surfaces under typical operating conditions. However, we nd that the saturation eects in the rotational response of polar solvent molecules, inherent to our nonlinear theory, are crucial for a qualitatively correct description of the ionic surfaces typical of the solid electrolyte interface.
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jdftx software for Joint Density functional theory
SoftwareX, 2017Co-Authors: Ravishankar Sundararaman, Kendra Letchworthweaver, Kathleen A Schwarz, Deniz Gunceler, Yalcin Ozhabes, T A AriasAbstract:Density-functional theory (DFT) has revolutionized computational prediction of atomic-scale properties from first principles in physics, chemistry and materials science. Continuing development of new methods is necessary for accurate predictions of new classes of materials and properties, and for connecting to nano- and mesoscale properties using coarse-grained theories. JDFTx is a fully-featured open-source electronic DFT software designed specifically to facilitate rapid development of new theories, models and algorithms. Using an algebraic formulation as an abstraction layer, compact C++11 code automatically performs well on diverse hardware including GPUs (Graphics Processing Units). This code hosts the development of Joint Density-functional theory (JDFT) that combines electronic DFT with classical DFT and continuum models of liquids for first-principles calculations of solvated and electrochemical systems. In addition, the modular nature of the code makes it easy to extend and interface with, facilitating the development of multi-scale toolkits that connect to ab initio calculations, e.g. photo-excited carrier dynamics combining electron and phonon calculations with electromagnetic simulations.
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the importance of nonlinear fluid response in Joint Density functional theory studies of battery systems
Modelling and Simulation in Materials Science and Engineering, 2013Co-Authors: Deniz Gunceler, Kendra Letchworthweaver, Ravishankar Sundararaman, Kathleen A Schwarz, T A AriasAbstract:Delivering the full benefits of first-principles calculations to battery materials demands the development of accurate and computationally efficient electronic structure methods that incorporate the effects of the electrolyte environment and electrode potential. Realistic electrochemical interfaces containing polar surfaces are beyond the regime of validity of existing continuum solvation theories developed for molecules, due to the presence of significantly stronger electric fields. We present an ab initio theory of the nonlinear dielectric and ionic response of solvent environments within the framework of Joint Density-functional theory, with precisely the same optimizable parameters as conventional polarizable continuum models. We demonstrate that the resulting nonlinear theory agrees with the standard linear models for organic molecules and metallic surfaces under typical operating conditions. However, we find that the saturation effects in the rotational response of polar solvent molecules, inherent to our nonlinear theory, are crucial for a qualitatively correct description of the ionic surfaces typical of the solid electrolyte interface.
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Joint Density functional theory of the electrode electrolyte interface application to fixed electrode potentials interfacial capacitances and potentials of zero charge
Physical Review B, 2012Co-Authors: Kendra Letchworthweaver, T A AriasAbstract:This work explores the use of Joint Density functional theory, an extension of Density functional theory for the ab initio description of electronic systems in thermodynamic equilibrium with a liquid environment, to describe electrochemical systems. After reviewing the physics of the underlying fundamental electrochemical concepts, we identify the mapping between commonly measured electrochemical observables and microscopically computable quantities within an, in principle, exact theoretical framework. We then introduce a simple, computationally efficient approximate functional which we find to be quite successful in capturing a priori basic electrochemical phenomena, including the capacitive Stern and diffusive Gouy-Chapman regions in the electrochemical double layer, quantitative values for interfacial capacitance, and electrochemical potentials of zero charge for a series of metals. We explore surface charging with applied potential and are able to place our ab initio results directly on the scale associated with the standard hydrogen electrode (SHE). Finally, we provide explicit details for implementation within standard Density functional theory software packages at negligible computational cost over standard calculations carried out within vacuum environments.
Chenggang Zhou - One of the best experts on this subject based on the ideXlab platform.
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wang landau algorithm for continuous models and Joint Density of states
Physical Review Letters, 2006Co-Authors: Chenggang Zhou, T C Schulthess, Stefan Torbrugge, D P LandauAbstract:We present a modified Wang-Landau algorithm for models with continuous degrees of freedom. We demonstrate this algorithm with the calculation of the Joint Density of states of ferromagnet Heisenberg models and a model polymer chain. The Joint Density of states contains more information than the Density of states of a single variable-energy, but is also much more time consuming to calculate. We present strategies to significantly speed up this calculation for large systems over a large range of energy and order parameter.
John N. Carter - One of the best experts on this subject based on the ideXlab platform.
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ICPR - A Joint Density Based Rank-Score Fusion for Soft Biometric Recognition at a Distance
2018 24th International Conference on Pattern Recognition (ICPR), 2018Co-Authors: Mark S. Nixon, John N. CarterAbstract:In order to improve recognition performance, fusion has become a key technique in the recent years. Compared with single-mode biometrics, the recognition rate of multi-modal biometric systems is improved and the final decision is more confident. This paper introduces a novel Joint Density distribution based rank-score fusion strategy that combines rank and score information. Recognition at a distance has only recently been of interest in soft biometrics. We create a new soft biometric database containing the human face, body and clothing attributes at three different distances to investigate the influence by distance on soft biometric fusion. A comparative study about our method and other state of the art rank level and score level fusion methods are also conducted in this paper. The experiments are performed using a soft biometric database we created. The results demonstrate the recognition performance is significantly improved by our proposed method.
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A Joint Density Based Rank-Score Fusion for Soft Biometric Recognition at a Distance
2018 24th International Conference on Pattern Recognition (ICPR), 2018Co-Authors: Mark S. Nixon, John N. CarterAbstract:In order to improve recognition performance, fusion has become a key technique in the recent years. Compared with single-mode biometrics, the recognition rate of multi-modal biometric systems is improved and the final decision is more confident. This paper introduces a novel Joint Density distribution based rank-score fusion strategy that combines rank and score information. Recognition at a distance has only recently been of interest in soft biometrics. We create a new soft biometric database containing the human face, body and clothing attributes at three different distances to investigate the influence by distance on soft biometric fusion. A comparative study about our method and other state of the art rank level and score level fusion methods are also conducted in this paper. The experiments are performed using a soft biometric database we created. The results demonstrate the recognition performance is significantly improved by our proposed method.
D P Landau - One of the best experts on this subject based on the ideXlab platform.
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wang landau algorithm for continuous models and Joint Density of states
Physical Review Letters, 2006Co-Authors: Chenggang Zhou, T C Schulthess, Stefan Torbrugge, D P LandauAbstract:We present a modified Wang-Landau algorithm for models with continuous degrees of freedom. We demonstrate this algorithm with the calculation of the Joint Density of states of ferromagnet Heisenberg models and a model polymer chain. The Joint Density of states contains more information than the Density of states of a single variable-energy, but is also much more time consuming to calculate. We present strategies to significantly speed up this calculation for large systems over a large range of energy and order parameter.
Kendra Letchworthweaver - One of the best experts on this subject based on the ideXlab platform.
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jdftx software for Joint Density functional theory
SoftwareX, 2017Co-Authors: Ravishankar Sundararaman, Kendra Letchworthweaver, Kathleen A Schwarz, Deniz Gunceler, Yalcin Ozhabes, T A AriasAbstract:Density-functional theory (DFT) has revolutionized computational prediction of atomic-scale properties from first principles in physics, chemistry and materials science. Continuing development of new methods is necessary for accurate predictions of new classes of materials and properties, and for connecting to nano- and mesoscale properties using coarse-grained theories. JDFTx is a fully-featured open-source electronic DFT software designed specifically to facilitate rapid development of new theories, models and algorithms. Using an algebraic formulation as an abstraction layer, compact C++11 code automatically performs well on diverse hardware including GPUs (Graphics Processing Units). This code hosts the development of Joint Density-functional theory (JDFT) that combines electronic DFT with classical DFT and continuum models of liquids for first-principles calculations of solvated and electrochemical systems. In addition, the modular nature of the code makes it easy to extend and interface with, facilitating the development of multi-scale toolkits that connect to ab initio calculations, e.g. photo-excited carrier dynamics combining electron and phonon calculations with electromagnetic simulations.
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the importance of nonlinear fluid response in Joint Density functional theory studies of battery systems
Modelling and Simulation in Materials Science and Engineering, 2013Co-Authors: Deniz Gunceler, Kendra Letchworthweaver, Ravishankar Sundararaman, Kathleen A Schwarz, T A AriasAbstract:Delivering the full benefits of first-principles calculations to battery materials demands the development of accurate and computationally efficient electronic structure methods that incorporate the effects of the electrolyte environment and electrode potential. Realistic electrochemical interfaces containing polar surfaces are beyond the regime of validity of existing continuum solvation theories developed for molecules, due to the presence of significantly stronger electric fields. We present an ab initio theory of the nonlinear dielectric and ionic response of solvent environments within the framework of Joint Density-functional theory, with precisely the same optimizable parameters as conventional polarizable continuum models. We demonstrate that the resulting nonlinear theory agrees with the standard linear models for organic molecules and metallic surfaces under typical operating conditions. However, we find that the saturation effects in the rotational response of polar solvent molecules, inherent to our nonlinear theory, are crucial for a qualitatively correct description of the ionic surfaces typical of the solid electrolyte interface.
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Joint Density functional theory of the electrode electrolyte interface application to fixed electrode potentials interfacial capacitances and potentials of zero charge
Physical Review B, 2012Co-Authors: Kendra Letchworthweaver, T A AriasAbstract:This work explores the use of Joint Density functional theory, an extension of Density functional theory for the ab initio description of electronic systems in thermodynamic equilibrium with a liquid environment, to describe electrochemical systems. After reviewing the physics of the underlying fundamental electrochemical concepts, we identify the mapping between commonly measured electrochemical observables and microscopically computable quantities within an, in principle, exact theoretical framework. We then introduce a simple, computationally efficient approximate functional which we find to be quite successful in capturing a priori basic electrochemical phenomena, including the capacitive Stern and diffusive Gouy-Chapman regions in the electrochemical double layer, quantitative values for interfacial capacitance, and electrochemical potentials of zero charge for a series of metals. We explore surface charging with applied potential and are able to place our ab initio results directly on the scale associated with the standard hydrogen electrode (SHE). Finally, we provide explicit details for implementation within standard Density functional theory software packages at negligible computational cost over standard calculations carried out within vacuum environments.
