The Experts below are selected from a list of 9369 Experts worldwide ranked by ideXlab platform
A.-m. S. Tremblay - One of the best experts on this subject based on the ideXlab platform.
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Entropy, frustration, and large thermopower of doped Mott insulators on the Fcc Lattice
Physical Review B, 2013Co-Authors: Louis-françois Arsenault, B. Sriram Shastry, Patrick Semon, A.-m. S. TremblayAbstract:Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the 3-dimensional Fcc Lattice over the whole range of fillings for intermediate and large interaction strength. Dynamical mean-field theory shows that when the density approaches half-filling, the Fcc Lattice at strong coupling exhibits a large low temperature Seebeck coefficient $S$. The largest effect occurs as one approaches $n=1$ from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the DC limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling the thermopower can be understood on entropic grounds.
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entropy frustration and large thermopower of doped mott insulators on the Fcc Lattice
Physical Review B, 2013Co-Authors: Louis-françois Arsenault, Patrick Semon, A.-m. S. Tremblay, Sriram B ShastryAbstract:Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the three-dimensional Fcc Lattice over the whole range of fillings for intermediate and large interaction strengths. Dynamical mean-field theory shows that when the density approaches half-filling, the Fcc Lattice at strong coupling exhibits a large low-temperature Seebeck coefficient $S$. The largest effect occurs as one approaches $n=1$ from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the dc limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling, the thermopower can be understood on entropic grounds.
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Benchmark of a modified iterated perturbation theory approach on the Fcc Lattice at strong coupling
Physical Review B, 2012Co-Authors: Louis-françois Arsenault, Patrick Semon, A.-m. S. TremblayAbstract:The Dynamical Mean-Field theory (DMFT) approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of non-interacting electrons. Iterated Perturbation Theory (IPT) has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact Continuous-Time Quantum Monte Carlo (CTQMC) solver, here we show that the standard implementation of IPT fails away from half-filling when the interaction strength is much larger than the bandwidth. We propose a slight modification to the IPT algorithm that replaces one of the equations by the requirement that double occupancy calculated with IPT gives the correct value. We call this method IPT-$D$. We recover the Fermi liquid ground state away from half-filling. The Fermi liquid parameters, density of states, chemical potential, energy and specific heat on the Fcc Lattice are calculated with both IPT-$D$ and CTQMC as benchmark examples. We also calculated the resistivity and the optical conductivity within IPT-$D$. Particle-hole asymmetry persists even at coupling twice the bandwidth. Several algorithms that speed up the calculations are described in appendices.
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benchmark of a modified iterated perturbation theory approach on the Fcc Lattice at strong coupling
Physical Review B, 2012Co-Authors: Louis-françois Arsenault, A.-m. S. Tremblay, P SemonAbstract:The dynamical mean-field theory approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of noninteracting electrons. Iterated perturbation theory (IPT) has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact continuous-time quantum Monte Carlo (CTQMC) solver, here we show that the standard implementation of IPT fails away from half-filling when the interaction strength is much larger than the bandwidth. We propose a slight modification to the IPT algorithm that replaces one of the equations by the requirement that double occupancy calculated with IPT gives the correct value. We call this method IPT-$D$. We recover the Fermi liquid ground state away from half-filling. The Fermi liquid parameters, density of states, chemical potential, energy, and specific heat on the Fcc Lattice are calculated with both IPT-$D$ and CTQMC as benchmark examples. We also calculated the resistivity and the optical conductivity within IPT-$D$. Particle-hole asymmetry persists even at coupling twice the bandwidth. A generalization to the multiorbital case is suggested. Several algorithms that speed up the calculations are described in appendixes.
Louis-françois Arsenault - One of the best experts on this subject based on the ideXlab platform.
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Entropy, frustration, and large thermopower of doped Mott insulators on the Fcc Lattice
Physical Review B, 2013Co-Authors: Louis-françois Arsenault, B. Sriram Shastry, Patrick Semon, A.-m. S. TremblayAbstract:Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the 3-dimensional Fcc Lattice over the whole range of fillings for intermediate and large interaction strength. Dynamical mean-field theory shows that when the density approaches half-filling, the Fcc Lattice at strong coupling exhibits a large low temperature Seebeck coefficient $S$. The largest effect occurs as one approaches $n=1$ from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the DC limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling the thermopower can be understood on entropic grounds.
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entropy frustration and large thermopower of doped mott insulators on the Fcc Lattice
Physical Review B, 2013Co-Authors: Louis-françois Arsenault, Patrick Semon, A.-m. S. Tremblay, Sriram B ShastryAbstract:Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the three-dimensional Fcc Lattice over the whole range of fillings for intermediate and large interaction strengths. Dynamical mean-field theory shows that when the density approaches half-filling, the Fcc Lattice at strong coupling exhibits a large low-temperature Seebeck coefficient $S$. The largest effect occurs as one approaches $n=1$ from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the dc limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling, the thermopower can be understood on entropic grounds.
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Benchmark of a modified iterated perturbation theory approach on the Fcc Lattice at strong coupling
Physical Review B, 2012Co-Authors: Louis-françois Arsenault, Patrick Semon, A.-m. S. TremblayAbstract:The Dynamical Mean-Field theory (DMFT) approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of non-interacting electrons. Iterated Perturbation Theory (IPT) has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact Continuous-Time Quantum Monte Carlo (CTQMC) solver, here we show that the standard implementation of IPT fails away from half-filling when the interaction strength is much larger than the bandwidth. We propose a slight modification to the IPT algorithm that replaces one of the equations by the requirement that double occupancy calculated with IPT gives the correct value. We call this method IPT-$D$. We recover the Fermi liquid ground state away from half-filling. The Fermi liquid parameters, density of states, chemical potential, energy and specific heat on the Fcc Lattice are calculated with both IPT-$D$ and CTQMC as benchmark examples. We also calculated the resistivity and the optical conductivity within IPT-$D$. Particle-hole asymmetry persists even at coupling twice the bandwidth. Several algorithms that speed up the calculations are described in appendices.
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benchmark of a modified iterated perturbation theory approach on the Fcc Lattice at strong coupling
Physical Review B, 2012Co-Authors: Louis-françois Arsenault, A.-m. S. Tremblay, P SemonAbstract:The dynamical mean-field theory approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of noninteracting electrons. Iterated perturbation theory (IPT) has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact continuous-time quantum Monte Carlo (CTQMC) solver, here we show that the standard implementation of IPT fails away from half-filling when the interaction strength is much larger than the bandwidth. We propose a slight modification to the IPT algorithm that replaces one of the equations by the requirement that double occupancy calculated with IPT gives the correct value. We call this method IPT-$D$. We recover the Fermi liquid ground state away from half-filling. The Fermi liquid parameters, density of states, chemical potential, energy, and specific heat on the Fcc Lattice are calculated with both IPT-$D$ and CTQMC as benchmark examples. We also calculated the resistivity and the optical conductivity within IPT-$D$. Particle-hole asymmetry persists even at coupling twice the bandwidth. A generalization to the multiorbital case is suggested. Several algorithms that speed up the calculations are described in appendixes.
Tapan Chatterji - One of the best experts on this subject based on the ideXlab platform.
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Spin waves in the Fcc Lattice antiferromagnet: competing interactions, frustration, and instabilities in the Hubbard model
Journal of Applied Physics, 2017Co-Authors: Avinash Singh, Shubhajyoti Mohapatra, Timothy Ziman, Tapan ChatterjiAbstract:Spin waves in the type-III ordered antiferromagnetic state of the frustrated t- t ′ Hubbard model on the face-centred-cubic (Fcc) Lattice are calculated to investigate finite-U-induced competing interaction and frustration effects on magnetic excitations and instabilities. Particularly strong competing interactions generated due to the interplay of Fcc Lattice geometry and magnetic order result in significant spin wave softening. The calculated spin wave dispersion is found to be in qualitative agreement with the measured spin wave dispersion in the pyrite mineral MnS2 obtained from inelastic neutron scattering experiments. Instabilities to other magnetic orders (type I, type II, spiral, non-collinear), as signalled by spin wave energies turning negative, are also discussed.
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spin waves in the af state of the t t hubbard model on the Fcc Lattice competing interactions frustration and instabilities
arXiv: Strongly Correlated Electrons, 2016Co-Authors: Avinash Singh, Shubhajyoti Mohapatra, Timothy Ziman, Tapan ChatterjiAbstract:Spin waves in the type-III ordered antiferromagnetic state of the frustrated $t$-$t'$ Hubbard model on the Fcc Lattice are calculated to investigate finite-$U$-induced competing interaction and frustration effects on magnetic excitations and instabilities. Particularly strong competing interactions generated due to interplay of Fcc Lattice geometry and magnetic order result in significant spin wave softening. The calculated spin wave dispersion is found to be in qualitative agreement with the measured spin wave dispersion in the pyrite mineral $\rm Mn S_2$ obtained from inelastic neutron scattering experiments. Instabilities to other magnetic orders (type I, type II, spiral, non-collinear), as signalled by spin wave energies turning negative, are also discussed.
An Pang Tsai - One of the best experts on this subject based on the ideXlab platform.
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Understanding the catalytic activity of nanoporous gold: Role of twinning in Fcc Lattice.
The Journal of chemical physics, 2017Co-Authors: Marian Krajčí, Satoshi Kameoka, An Pang TsaiAbstract:Nanoporous gold (NPG) prepared by de-alloying Al2Au exhibits correlation between the high catalytic reactivity towards CO oxidation and the density of twinning defects in the Fcc Lattice of NPG. It was also discovered that on the internal surface of NPG, quite common twinning defects can create close-packed rows of six-coordinated catalytically active Au atoms denoted as W-chains. In this work, using density functional theory methods, we investigate energy conditions for formation, thermal stability, and chemical reactivity of these active sites. The possibility of dioxygen chemisorption on various surface sites is studied in detail. A contribution from the dispersion interactions is also considered. The calculated surface density of the active six-coordinated atoms in NPG comparable with that of supported gold nanoparticle catalysts, exothermic chemisorption of dioxygen, and the energy profiles of reaction pathways for CO oxidation indicate that the six-coordinated sites created by twinning can significantly contribute to the catalytic activity of NPG.
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Twinning in Fcc Lattice creates low-coordinated catalytically active sites in porous gold.
The Journal of chemical physics, 2016Co-Authors: Marian Krajčí, Satoshi Kameoka, An Pang TsaiAbstract:We describe a new mechanism for creation of catalytically active sites in porous gold. Samples of porous gold prepared by de-alloying Al2Au exhibit a clear correlation between the catalytic reactivity towards CO oxidation and structural defects in the Fcc Lattice of Au. We have found that on the stepped {211} surfaces quite common twin boundary defects in the bulk structure of porous gold can form long close-packed rows of atoms with the coordination number CN = 6. DFT calculations confirm that on these low-coordinated Au sites dioxygen chemisorbs and CO oxidation can proceed via the Langmuir-Hinshelwood mechanism with the activation energy of 37 kJ/mol or via the CO-OO intermediate with the energy barrier of 19 kJ/mol. The existence of the twins in porous gold is stabilized by the surface energy.
Patrick Semon - One of the best experts on this subject based on the ideXlab platform.
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Entropy, frustration, and large thermopower of doped Mott insulators on the Fcc Lattice
Physical Review B, 2013Co-Authors: Louis-françois Arsenault, B. Sriram Shastry, Patrick Semon, A.-m. S. TremblayAbstract:Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the 3-dimensional Fcc Lattice over the whole range of fillings for intermediate and large interaction strength. Dynamical mean-field theory shows that when the density approaches half-filling, the Fcc Lattice at strong coupling exhibits a large low temperature Seebeck coefficient $S$. The largest effect occurs as one approaches $n=1$ from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the DC limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling the thermopower can be understood on entropic grounds.
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entropy frustration and large thermopower of doped mott insulators on the Fcc Lattice
Physical Review B, 2013Co-Authors: Louis-françois Arsenault, Patrick Semon, A.-m. S. Tremblay, Sriram B ShastryAbstract:Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the three-dimensional Fcc Lattice over the whole range of fillings for intermediate and large interaction strengths. Dynamical mean-field theory shows that when the density approaches half-filling, the Fcc Lattice at strong coupling exhibits a large low-temperature Seebeck coefficient $S$. The largest effect occurs as one approaches $n=1$ from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the dc limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling, the thermopower can be understood on entropic grounds.
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Benchmark of a modified iterated perturbation theory approach on the Fcc Lattice at strong coupling
Physical Review B, 2012Co-Authors: Louis-françois Arsenault, Patrick Semon, A.-m. S. TremblayAbstract:The Dynamical Mean-Field theory (DMFT) approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of non-interacting electrons. Iterated Perturbation Theory (IPT) has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact Continuous-Time Quantum Monte Carlo (CTQMC) solver, here we show that the standard implementation of IPT fails away from half-filling when the interaction strength is much larger than the bandwidth. We propose a slight modification to the IPT algorithm that replaces one of the equations by the requirement that double occupancy calculated with IPT gives the correct value. We call this method IPT-$D$. We recover the Fermi liquid ground state away from half-filling. The Fermi liquid parameters, density of states, chemical potential, energy and specific heat on the Fcc Lattice are calculated with both IPT-$D$ and CTQMC as benchmark examples. We also calculated the resistivity and the optical conductivity within IPT-$D$. Particle-hole asymmetry persists even at coupling twice the bandwidth. Several algorithms that speed up the calculations are described in appendices.
