The Experts below are selected from a list of 14736 Experts worldwide ranked by ideXlab platform
Daniel J Gezelter - One of the best experts on this subject based on the ideXlab platform.
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polarizable potentials for metals the Density readjusting embedded atom method dr eam
Physical Review B, 2019Co-Authors: Hemanta Bhattarai, Kathie E Newman, Daniel J GezelterAbstract:In simulations of metallic interfaces, a critical aspect of metallic behavior is missing from the some of the most widely used classical molecular dynamics force fields. We present a modification of the embedded atom method (EAM) which allows for Electronic polarization of the metal by treating the Valence Density around each atom as a fluctuating dynamical quantity. The densities are represented by a set of additional fluctuating variables (and their conjugate momenta) which are propagated along with the nuclear coordinates. This ``Density readjusting EAM'' (DR-EAM) preserves nearly all of the useful qualities of traditional EAM, including bulk elastic properties and surface energies. However, it also allows Valence Electron Density to migrate through the metal in response to external perturbations. We show that DR-EAM can successfully model polarization in response to external charges, capturing the image charge effect in atomistic simulations. DR-EAM also captures some of the behavior of metals in the presence of uniform electric fields, predicting surface charging and shielding internal to the metal. We further show that it predicts charge transfer between the constituent atoms in alloys, leading to novel predictions about unit cell geometries in layered L$1_0$ structures.
Steven Johnston - One of the best experts on this subject based on the ideXlab platform.
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multiorbital charge Density wave excitations and concomitant phonon anomalies in bi2sr2lacuo6 δ
Proceedings of the National Academy of Sciences of the United States of America, 2020Co-Authors: Abhishek Nag, Jonathan Pelliciari, H C Robarts, Andrew Walters, M Garciafernandez, H Eisaki, Dongjoon Song, Hong Ding, Steven JohnstonAbstract:Charge-Density waves (CDWs) are ubiquitous in underdoped cuprate superconductors. As a modulation of the Valence Electron Density, CDWs in hole-doped cuprates possess both Cu-3d and O-2p orbital character owing to the strong hybridization of these orbitals near the Fermi level. Here, we investigate underdoped Bi2Sr1.4La0.6CuO6+δ using resonant inelastic X-ray scattering (RIXS) and find that a short-range CDW exists at both Cu and O sublattices in the copper-oxide (CuO2) planes with a comparable periodicity and correlation length. Furthermore, we uncover bond-stretching and bond-buckling phonon anomalies concomitant to the CDWs. Comparing to slightly overdoped Bi2Sr1.8La0.2CuO6+δ, where neither CDWs nor phonon anomalies appear, we highlight that a sharp intensity anomaly is induced in the proximity of the CDW wavevector (QCDW) for the bond-buckling phonon, in concert with the diffused intensity enhancement of the bond-stretching phonon at wavevectors much greater than QCDW. Our results provide a comprehensive picture of the quasistatic CDWs, their dispersive excitations, and associated Electron-phonon anomalies, which are key for understanding the competing Electronic instabilities in cuprates.
Jonathan Pelliciari - One of the best experts on this subject based on the ideXlab platform.
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multiorbital charge Density wave excitations and concomitant phonon anomalies in bi2sr2lacuo6 δ
Proceedings of the National Academy of Sciences of the United States of America, 2020Co-Authors: Abhishek Nag, Jonathan Pelliciari, H C Robarts, Andrew Walters, M Garciafernandez, H Eisaki, Dongjoon Song, Hong Ding, Steven JohnstonAbstract:Charge-Density waves (CDWs) are ubiquitous in underdoped cuprate superconductors. As a modulation of the Valence Electron Density, CDWs in hole-doped cuprates possess both Cu-3d and O-2p orbital character owing to the strong hybridization of these orbitals near the Fermi level. Here, we investigate underdoped Bi2Sr1.4La0.6CuO6+δ using resonant inelastic X-ray scattering (RIXS) and find that a short-range CDW exists at both Cu and O sublattices in the copper-oxide (CuO2) planes with a comparable periodicity and correlation length. Furthermore, we uncover bond-stretching and bond-buckling phonon anomalies concomitant to the CDWs. Comparing to slightly overdoped Bi2Sr1.8La0.2CuO6+δ, where neither CDWs nor phonon anomalies appear, we highlight that a sharp intensity anomaly is induced in the proximity of the CDW wavevector (QCDW) for the bond-buckling phonon, in concert with the diffused intensity enhancement of the bond-stretching phonon at wavevectors much greater than QCDW. Our results provide a comprehensive picture of the quasistatic CDWs, their dispersive excitations, and associated Electron-phonon anomalies, which are key for understanding the competing Electronic instabilities in cuprates.
Wei Liu - One of the best experts on this subject based on the ideXlab platform.
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Influence of yttrium on the interface Valence Electron Density of thermal barrier coatings
Materials Chemistry and Physics, 2007Co-Authors: Wei LiuAbstract:Abstract Most of the bonding layers of thermal barrier coatings contain some yttrium to improve the physical consistency of the substrate and the ceramics layer. But the reason of the improvement and the proper yttrium content are not clear. In this paper, the Valence Electron densities ρh k l and ρ u v w of the two sides and their difference Δρmin of the bonding layer/ceramic layer interface of thermal barrier coatings are calculated with the empirical Electron theory in solids and molecules at various bonding layer yttrium content. The results show the following. The addition of yttrium has beneficial effect on the decrease of the interface stress because it decreases the Δρmin. The addition of yttrium can also increase the Valence Electron Density ρh k l or ρ u v w of the interface and so increase the interface cohesion force. The most effective yttrium content is at 0.4 wt% or so. The deductions accord with the actual coating, so the method can be applied to design the composition of the bonding layer of thermal barrier coatings. Furthermore, the calculation and the analysis methods of the interface Valence Electron densities can also be extended to other crystal coatings or composites with special orientation relationship, no matter the interface is a alloy/alloy one, a ceramics/alloy one or a ceramics/ceramics one.
Hemanta Bhattarai - One of the best experts on this subject based on the ideXlab platform.
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polarizable potentials for metals the Density readjusting embedded atom method dr eam
Physical Review B, 2019Co-Authors: Hemanta Bhattarai, Kathie E Newman, Daniel J GezelterAbstract:In simulations of metallic interfaces, a critical aspect of metallic behavior is missing from the some of the most widely used classical molecular dynamics force fields. We present a modification of the embedded atom method (EAM) which allows for Electronic polarization of the metal by treating the Valence Density around each atom as a fluctuating dynamical quantity. The densities are represented by a set of additional fluctuating variables (and their conjugate momenta) which are propagated along with the nuclear coordinates. This ``Density readjusting EAM'' (DR-EAM) preserves nearly all of the useful qualities of traditional EAM, including bulk elastic properties and surface energies. However, it also allows Valence Electron Density to migrate through the metal in response to external perturbations. We show that DR-EAM can successfully model polarization in response to external charges, capturing the image charge effect in atomistic simulations. DR-EAM also captures some of the behavior of metals in the presence of uniform electric fields, predicting surface charging and shielding internal to the metal. We further show that it predicts charge transfer between the constituent atoms in alloys, leading to novel predictions about unit cell geometries in layered L$1_0$ structures.
