This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how LDA+U can describe Mott insulators, charge order, spin order, orbital order, and phase transitions. Applications included Fe3O4, KCuF3, Pr1-xCaxMnO3, and LaCoO3. It also introduces the dynamical mean-field theory (DMFT) method, which goes beyond LDA+U by including dynamical correlations. DMFT maps the lattice problem to an effective impurity problem, which can be solved using techniques like quantum Monte Carlo. The document outlines the DMFT self-consistency cycle and implementation of QMC as an impurity solver.
Electronic structure of strongly correlated materials Part II V.AnisimovABDERRAHMANE REGGAD
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how these methods can accurately model Mott insulators, charge order, spin order, orbital order, and other phenomena. Specific examples discussed include charge ordering in Fe3O4, orbital ordering in KCuF3 and LaMnO3, and the spin state of Co3+ in LaCoO3. It also outlines the theoretical foundations and computational schemes of the LDA+U and LDA+DMFT methods, such as how the quantum Monte Carlo method can be used to solve the effective impurity problem in LDA+DMFT.
Electrical transport and magnetic interactions in 3d and 5d transition metal ...ABDERRAHMANE REGGAD
The document discusses electrical transport and magnetic interactions in 3d and 5d transition metal oxides. It summarizes that for decades, transition metal oxides have been explored where exotic states like high-Tc superconductivity and colossal magnetoresistance emerge due to cooperative interactions between spin, charge, and orbital degrees of freedom. The document then examines various phenomena in transition metal oxides including Mott insulators, double exchange mechanism, and the Kitaev-Heisenberg model observed in iridate compounds like Na2IrO3 which may realize a spin liquid ground state.
Molecular dynamics simulations of ferroelectrics with feram codeTakeshi Nishimatsu
This document discusses ferroelectric materials and molecular dynamics (MD) simulations of their properties using an effective Hamiltonian approach. Key points include:
1) Feram is an MD simulation code that models perovskite ferroelectrics like BaTiO3 using a first-principles based effective Hamiltonian.
2) Simulations of bulk BaTiO3 and PbTiO3 reproduce their phase transitions and domain structures.
3) Simulations of thin-film capacitors show the effect of "dead layers" between ferroelectrics and electrodes on polarization.
4) Direct MD simulations of the electrocaloric effect in BaTiO3 predict a temperature change under applied and removed electric fields.
Plasmon Enhanced Internal Quantum Efficiency of CdSe/ZnS Quantum Dotsijrap
The effects of surface plasmon oscillations on the radiative recombination rate and internal quantum efficiency of silver coated CdSe/ZnS quantum dots imbedded in quartz matrix is studied theoretically and
numerically. The analysis is carried out by introducing the local field enhancement factor for the description of the dielectric function of the quantum dots together with the modified Drude model for the metal-coat that takes into account the effects of interband transitions and the size dependent damping
parameter. It is found out that the internal quantum efficiency of photoluminescence emission of the metalcoated CdSe/ZnS quantum dots is enhanced by about 5-folds compared with the quantum dots without metal-coat. Moreover, increasing the metal fraction of the coated CdSe/ZnS quantum dots from 0.80 to 0.92 results in a significant increase of the intensity that is accompanied by a blue-shift of the quantum efficiency curves. The results obtained can be utilized in the design and fabrication of optoelectronic devices that require high intensity of photoluminescence emission.
Theoretical picture: magnetic impurities, Zener model, mean-field theoryABDERRAHMANE REGGAD
The document summarizes the theoretical picture of dilute magnetic semiconductors (DMS). It describes the Zener model where magnetic impurities interact with charge carriers via exchange interaction. It then discusses the mean field approximation used to calculate the Curie temperature. For higher doping concentrations, a virtual crystal approximation is used to replace impurity spins with a smooth spin density. The model explains several experimental observations but cannot explain some properties like the shape of magnetization curves. At very low doping, a bound magnetic polaron model applies where carriers hop between localized acceptor levels aligned with impurity spins.
Maidana - Modification of particle accelerators for cargo inspection applicat...Carlos O. Maidana
As part of an accelerator based Cargo Inspection System, studies were made to develop a Cabinet Safe System by Optimization of the Beam Optics of Microwave Linear Accelerators of the IAC-Varian series working on the S-band and standing wave pi/2 mode. Measurements, modeling and simulations of the main subsystems were done and a Multiple Solenoidal System was designed.
This Cabinet Safe System based on a Multiple Solenoidal System minimizes the radiation field generated by the low efficiency of the microwave accelerators by optimizing the RF waveguide system and by also trapping secondaries generated in the accelerator head. These secondaries are generated mainly due to instabilities in the exit window region and particles backscattered from the target. The electron gun was also studied and software for its right mechanical design and for its optimization was developed as well. Besides the standard design method, an optimization of the injection process is accomplished by slightly modifying the gun configuration and by placing a solenoid on the waist position while avoiding threading the cathode with the magnetic flux generated.
The Multiple Solenoidal System and the electron gun optimization are the backbone of a Cabinet Safe System that could be applied not only to the 25 MeV IAC-Varian microwave accelerators but, by extension, to machines of different manufacturers as well. Thus, they constitute the main topic of this paper.
Electronic structure of strongly correlated materials Part II V.AnisimovABDERRAHMANE REGGAD
This document summarizes applications of the LDA+U and LDA+DMFT methods to strongly correlated materials. It discusses how these methods can accurately model Mott insulators, charge order, spin order, orbital order, and other phenomena. Specific examples discussed include charge ordering in Fe3O4, orbital ordering in KCuF3 and LaMnO3, and the spin state of Co3+ in LaCoO3. It also outlines the theoretical foundations and computational schemes of the LDA+U and LDA+DMFT methods, such as how the quantum Monte Carlo method can be used to solve the effective impurity problem in LDA+DMFT.
Electrical transport and magnetic interactions in 3d and 5d transition metal ...ABDERRAHMANE REGGAD
The document discusses electrical transport and magnetic interactions in 3d and 5d transition metal oxides. It summarizes that for decades, transition metal oxides have been explored where exotic states like high-Tc superconductivity and colossal magnetoresistance emerge due to cooperative interactions between spin, charge, and orbital degrees of freedom. The document then examines various phenomena in transition metal oxides including Mott insulators, double exchange mechanism, and the Kitaev-Heisenberg model observed in iridate compounds like Na2IrO3 which may realize a spin liquid ground state.
Molecular dynamics simulations of ferroelectrics with feram codeTakeshi Nishimatsu
This document discusses ferroelectric materials and molecular dynamics (MD) simulations of their properties using an effective Hamiltonian approach. Key points include:
1) Feram is an MD simulation code that models perovskite ferroelectrics like BaTiO3 using a first-principles based effective Hamiltonian.
2) Simulations of bulk BaTiO3 and PbTiO3 reproduce their phase transitions and domain structures.
3) Simulations of thin-film capacitors show the effect of "dead layers" between ferroelectrics and electrodes on polarization.
4) Direct MD simulations of the electrocaloric effect in BaTiO3 predict a temperature change under applied and removed electric fields.
Plasmon Enhanced Internal Quantum Efficiency of CdSe/ZnS Quantum Dotsijrap
The effects of surface plasmon oscillations on the radiative recombination rate and internal quantum efficiency of silver coated CdSe/ZnS quantum dots imbedded in quartz matrix is studied theoretically and
numerically. The analysis is carried out by introducing the local field enhancement factor for the description of the dielectric function of the quantum dots together with the modified Drude model for the metal-coat that takes into account the effects of interband transitions and the size dependent damping
parameter. It is found out that the internal quantum efficiency of photoluminescence emission of the metalcoated CdSe/ZnS quantum dots is enhanced by about 5-folds compared with the quantum dots without metal-coat. Moreover, increasing the metal fraction of the coated CdSe/ZnS quantum dots from 0.80 to 0.92 results in a significant increase of the intensity that is accompanied by a blue-shift of the quantum efficiency curves. The results obtained can be utilized in the design and fabrication of optoelectronic devices that require high intensity of photoluminescence emission.
Theoretical picture: magnetic impurities, Zener model, mean-field theoryABDERRAHMANE REGGAD
The document summarizes the theoretical picture of dilute magnetic semiconductors (DMS). It describes the Zener model where magnetic impurities interact with charge carriers via exchange interaction. It then discusses the mean field approximation used to calculate the Curie temperature. For higher doping concentrations, a virtual crystal approximation is used to replace impurity spins with a smooth spin density. The model explains several experimental observations but cannot explain some properties like the shape of magnetization curves. At very low doping, a bound magnetic polaron model applies where carriers hop between localized acceptor levels aligned with impurity spins.
Maidana - Modification of particle accelerators for cargo inspection applicat...Carlos O. Maidana
As part of an accelerator based Cargo Inspection System, studies were made to develop a Cabinet Safe System by Optimization of the Beam Optics of Microwave Linear Accelerators of the IAC-Varian series working on the S-band and standing wave pi/2 mode. Measurements, modeling and simulations of the main subsystems were done and a Multiple Solenoidal System was designed.
This Cabinet Safe System based on a Multiple Solenoidal System minimizes the radiation field generated by the low efficiency of the microwave accelerators by optimizing the RF waveguide system and by also trapping secondaries generated in the accelerator head. These secondaries are generated mainly due to instabilities in the exit window region and particles backscattered from the target. The electron gun was also studied and software for its right mechanical design and for its optimization was developed as well. Besides the standard design method, an optimization of the injection process is accomplished by slightly modifying the gun configuration and by placing a solenoid on the waist position while avoiding threading the cathode with the magnetic flux generated.
The Multiple Solenoidal System and the electron gun optimization are the backbone of a Cabinet Safe System that could be applied not only to the 25 MeV IAC-Varian microwave accelerators but, by extension, to machines of different manufacturers as well. Thus, they constitute the main topic of this paper.
Atomic data and spectral models for lowly ionized iron-peak speciesAstroAtom
This document discusses the need for reliable atomic data and spectral models for lowly ionized iron-peak species like Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. Current models are inaccurate, with predicted line intensities disagreeing with observations by factors of several. The goals of the project are to compute new atomic data, construct improved spectral and opacity models, and implement the models in photoionization codes. The document outlines challenges in modeling these ions and describes ongoing work using relativistic R-matrix methods to calculate improved collision strengths and photoionization cross sections.
This dissertation investigates various aspects of helimagnets. Helimagnets are magnets with spins aligned in helical order at low temperatures. It exists in materials of crystal structure lacking the spatial inversion symmetry. The helical order is due to the Dzyaloshinskii-Moriya (DM) mechanism. Examples of helimagnets include MnSi, FeGe and Fe<sub>1-<italic>x</italic></sub>Co<sub><itaic>x</italic></sub>Si. A field theory appropriate for such magnets is used to derive the phase diagram in a mean-field approximation. The helical phase, the conical phase, the columnar phase and the non-Fermi-liquid (NFL) region in the paramagnetic phase are discussed. It is shown that the orientation of the helical vector along an external magnetic field within the conical phase occurs via two distinct phase transitions. The columnar phase, believed to be a Skyrmion lattice, is found to exist as Abrikosov Skyrmions near the helimagnetic phase boundary, and the core-to-core distance is estimated. The Goldstone modes that result from the long-range order in the various phases are determined, and their consequences for electronic properties, in particular, the specific heat, single-particle relaxation rate and the electrical conductivity, are derived. In addition, Skyrmion gases and lattices in helimagnets are studied, and the size of a Skyrmion in various phases is estimated. For isolated Skyrmions, the long distance tail is related to the magnetization correlation functions and exhibits power-law decay if the phase spontaneously breaks a continuous symmetry, but decays exponentially otherwise. The size of a Skyrmion is found to depend on a number of length scales. These length scales are related to the strength of DM interaction, the temperature, and the external magnetic field.
The public trial lecture presented by Mohammadreza Nematollahi on 8th of October 2014 at Norwegian University of Science and Technology. The theoretical models and the experimental progress of highly mismatched alloys, as well as their optoelectronic applications are covered.
Analysis Of Carbon Nanotubes And Quantum Dots In A Photovoltaic Device Slide ...M. Faisal Halim
Francis' presentation to Louis Stokes Association for Minority Participation. Since I co-authored this work I think I have the right to a copy. I was the graduate student Francis was working with.
1) The study investigated the effect of adding zirconium oxide nanoparticles to carbon black electrode materials on surface morphology and electrochemical performance.
2) Scanning electron microscopy showed that adding nanoparticles partially filled gaps between carbon black particles, increasing the specific surface area available for charge storage.
3) Electrochemical analysis found that increasing nanoparticle content initially increased total charge storage due to higher surface area and pseudocapacitive charge storage, but further increases reduced performance due to higher electrode resistance.
Magnetic and Chemical Order in Heusler Alloys Containing Neodymium and Moiybd...IJERA Editor
Saturation magnetization X-ray and neutron diffraction measurements have been made on alloys at the
compositions Nd2MoCd’, Nd2MoZn’, Nd2MoCu, Nd2MoTi, Nd2MoAg, Nd2MoZr and NdMoZr. The alloys
containing Cu and Ag have fully ordered Heusler, L21, Chemical structure. Nd2MoCd is similarly ordered but
with some partial Mo-Cd disorder. The alloys Nd2MoZn and Nd2MoTi each contain a secondary phase in
addition to the primary Heusler phase Nd2MoZr contains the two phases Nd122MoZr and Nd and NdMoZr is
ordered in the Clb structure. The alloys containing the group IIIB or IVB elements Cd, Zn, Cu, Ti or Ag are
ferromagnetically ordered, with the magnetic moment associated with the ordered Nd sites. The two alloys
containing the group VB elements Zr have vacant chemically ordered ‘Nd’ sites but are paramagnetic.
Effect of sodium doping on thermal properties of perovskite r mn o3 for poten...Alexander Decker
This document discusses the effect of sodium doping on the thermal properties of perovskite rare earth manganites RMnO3 for potential magnetoelectric applications. It studies the thermal, elastic, and cohesive properties of sodium-doped rare earth manganites R1-xNaxMnO3 (R3+ = La, Pr, Tb) using a modified rigid ion model and atom in molecules theory. It finds that sodium doping increases the A-site cation radius, affecting properties like lattice specific heat, Debye temperature, thermal expansion, bulk modulus, and cohesive energy. These thermal properties are important for determining the compatibility of components in thermoelectric devices and revealing electron-lattice coupling in
This document presents an interaction model to describe dipolar and superexchange interactions in cobalt-doped titanium dioxide thin films. It describes the relevant energy terms in the Hamiltonian, including Zeeman, crystalline anisotropy, dipolar interaction, and effective exchange energies. Simulation results using a Metropolis algorithm show magnetization curves as a function of temperature and field that resemble paramagnetic behavior but do not follow Curie-Weiss law. Zero-field cooled and field cooled magnetization curves are also presented from the simulations.
Ferroelectric nanostructures and their processing issues♪♫•*¨ *•.¸¸
This document discusses ferroelectric nanostructures and their processing issues. It covers several topics including important events in the history of ferroelectricity, factors that influence ferroelectric properties at the nanoscale, and different invasive and non-invasive approaches for processing ferroelectric nanostructures such as top-down methods like focused ion beam patterning and bottom-up methods like self-assembly. Potential applications of ferroelectric nanostructures are also mentioned, including data storage, piezoelectric actuators, and pyroelectric detectors.
The document discusses colossal magnetoresistance (CMR), where the electrical resistance of certain materials changes dramatically with an applied magnetic field. CMR was first observed in mixed-valence manganite materials and is caused by interactions between the electron spin, orbit, and lattice structure. Potential applications include smaller, higher capacity data storage devices. CMR remains an active area of research in physics and materials science due to its fundamental complexity and technological promise.
This document discusses theoretical and experimental studies on viologen-containing 1,1'-binaphthyls as potential near-infrared chiroptically switching materials. Theoretical modeling was used to correlate chiroptical properties with molecular geometry, showing maximal properties for a twisting angle of 60° and interchromophoric distance of 3.9 nm. Two chiral molecules containing viologen groups attached to a 1,1'-binaphthyl core through short spacers were synthesized and showed strong circular dichroism bands in the visible and near-infrared regions upon electrochemical reduction, demonstrating their potential as chiroptical switches. The cyclic molecule showed stronger chiroptical properties than the open-ring analogue.
Electronic structure of strongly correlated materials Part III V.AnisimovABDERRAHMANE REGGAD
This document discusses results from DFT+DMFT calculations on various strongly correlated materials. It summarizes calculations showing a strongly correlated metal state in SrVO3 with a lower Hubbard band, a Mott insulator transition in V2O3 accompanied by a small structural change, and heavy fermion behavior in Li2VO4 without f-electrons. It also discusses calculations of the charge transfer insulator NiO, pressure-induced transitions in MnO and Fe2O3, correlated covalent insulators FeSi and FeSb2, superconductivity in LaOFeAs, Jahn-Teller distortions and orbital ordering in KCuF3, and f-electron localization in cerium. The document
Ultrafast response of metal-semiconductor hybrid.pptxSabinaGurung12
This thesis presents an extensive study of self-organizatized synthesis of hybrid
nanostructure and their characterization using a combination of spectroscopic and microscopic
techniques, supported by theoretical modelling. Apart from the various potential applications of the
hybrid nanostructures reported, this thesis also provides an insight on the synergistic interaction
between Ag NP and CdTe QD. The future interest of this work involves utilization of these hybrid
nanostructure colloid for various applications like in optoelectronics and solar cells by transforming
the colloidal sample into thin films.
This document discusses the effect of heating rate on the structural and optical properties of silicon and magnesium co-doped zirconia nanopowders prepared by a sol-gel method. X-ray diffraction analysis showed that different heating rates between 1-10°C/min affected the formation of tetragonal and cubic phases, crystallinity, and particle size. Ultraviolet-visible spectroscopy showed that the band gap energy of the doped zirconia crystals decreased depending on the heating rate, with a minimum band gap of around 3-3.2 eV.
This document discusses simulating UV-vis spectra of methyl viologen and its radical cation using time-dependent density functional theory (TD-DFT). It optimizes the geometries of methyl viologen and its radical cation using DFT and discusses using TD-DFT with a 6-311G** basis set to simulate the UV-vis spectra. It also plans to simulate the UV-vis spectra using a multi-reference method called CASPT2.
The document discusses Crystal Field Theory, which explains the bonding in transition metal complexes. It describes how the electrostatic interaction between ligand electrons and metal d-orbitals results in a splitting of the d-orbital energies. In an octahedral field, the t2g orbitals are stabilized more than the eg orbitals. Crystal Field Theory can explain properties like electronic spectra, magnetic moments, and color of complexes. The magnitude of splitting depends on factors like the metal ion, its charge, the ligands, and can be represented by the crystal field splitting energy Δo.
Synthesis and charaterization of la1 x srxmno3 perovskite nanoparticlesMai Trần
In recent times perovskite materials are extensively studied and have attracted much attention because they exhibit interesting the properties, showing potential applications in commercial, technical and biomedical. In Vietnam, perovskite materials be of interest research and applications are strong but with major research direction is to go deep into the electrical properties and the magnetic properties. The Lanthanum Strontium manganite is a perovskite-based crystal-structured ceramic material with the formula of La1-xSrxMnO3, where x describes the doping ratio. It has attracted much attention due to its good magnetic, electrical, and catalytic properties and is becoming an attractive possibility material in several biomedical applications, particularly with nano-size. In industry, this material is commonly used in as a cathode material in commercially produced solid oxide fuel cells. In this thesis, we present the Perovskite nanoparticles La1-xSrxMnO3 were successfully synthesized of the nanosize La1-xSrxMnO3 at x = 0; 0.1; 0.2; 0.3 and 0.4 which prepared by a modified sol-gel method. Structure and magnetic properties of them were systematically investigated in dependence on doped Sr ratio x. The structure was investigated by XRD and show slightly changed but magnetic properties varied strongly with changing the doping ratio x. Magnetic properties of samples were studied by Vibrating Sample Mode of Physical Properties Measurement System show at the room temperature, the samples show superparamagnetic properties with high saturated magnetization MS of 57 emu/g which strongly dependents on the doped Sr ratio x.
This document discusses theoretical atomic and molecular physics research being conducted on recombination lines in nebulae spectra. The research group is investigating two recombination processes, radiative and dielectronic recombination, using atomic structure and R-matrix codes. They are studying carbon and magnesium ions to analyze planetary nebulae and draw conclusions about nebula conditions and compositions.
Coordination Compounds - CHARACTERIZATION AND OVERVIEW, DETECTION OF COMPLEX FORMATION, Formation of precipitate, Conductivity measurements , Change in chemical behaviour, Spectral methods, Magnetic Method, Spectral Calculations, Term symbols, Mulliken term symbols, Orgel diagrams - d1 configuration in Oh environment , d9 configuration in Oh environment, d1 configuration in Oh environment, Limitations Tanabe sugano diagrams, d2 configuration in Oh environment , Advantages over Orgel’s, Racah parameters
The document summarizes the metal-insulator transition in VO2, which occurs at 340K. In the metallic phase, VO2 exhibits bad metal behavior with short electron mean free paths. The insulating phase has two possible structures - M1 and M2. M1 involves pairing of V atoms and splitting of orbitals. M2 involves formation of zig-zag V chains. The transition may involve both Mott-Hubbard localization and a Peierls instability driven by soft phonon modes near the R point of the Brillouin zone. Precise values are estimated for the electronic parameters characterizing the insulating M1 phase, including Hubbard U, spin gap Δσ, and charge gap Δρ.
Atomic data and spectral models for lowly ionized iron-peak speciesAstroAtom
This document discusses the need for reliable atomic data and spectral models for lowly ionized iron-peak species like Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. Current models are inaccurate, with predicted line intensities disagreeing with observations by factors of several. The goals of the project are to compute new atomic data, construct improved spectral and opacity models, and implement the models in photoionization codes. The document outlines challenges in modeling these ions and describes ongoing work using relativistic R-matrix methods to calculate improved collision strengths and photoionization cross sections.
This dissertation investigates various aspects of helimagnets. Helimagnets are magnets with spins aligned in helical order at low temperatures. It exists in materials of crystal structure lacking the spatial inversion symmetry. The helical order is due to the Dzyaloshinskii-Moriya (DM) mechanism. Examples of helimagnets include MnSi, FeGe and Fe<sub>1-<italic>x</italic></sub>Co<sub><itaic>x</italic></sub>Si. A field theory appropriate for such magnets is used to derive the phase diagram in a mean-field approximation. The helical phase, the conical phase, the columnar phase and the non-Fermi-liquid (NFL) region in the paramagnetic phase are discussed. It is shown that the orientation of the helical vector along an external magnetic field within the conical phase occurs via two distinct phase transitions. The columnar phase, believed to be a Skyrmion lattice, is found to exist as Abrikosov Skyrmions near the helimagnetic phase boundary, and the core-to-core distance is estimated. The Goldstone modes that result from the long-range order in the various phases are determined, and their consequences for electronic properties, in particular, the specific heat, single-particle relaxation rate and the electrical conductivity, are derived. In addition, Skyrmion gases and lattices in helimagnets are studied, and the size of a Skyrmion in various phases is estimated. For isolated Skyrmions, the long distance tail is related to the magnetization correlation functions and exhibits power-law decay if the phase spontaneously breaks a continuous symmetry, but decays exponentially otherwise. The size of a Skyrmion is found to depend on a number of length scales. These length scales are related to the strength of DM interaction, the temperature, and the external magnetic field.
The public trial lecture presented by Mohammadreza Nematollahi on 8th of October 2014 at Norwegian University of Science and Technology. The theoretical models and the experimental progress of highly mismatched alloys, as well as their optoelectronic applications are covered.
Analysis Of Carbon Nanotubes And Quantum Dots In A Photovoltaic Device Slide ...M. Faisal Halim
Francis' presentation to Louis Stokes Association for Minority Participation. Since I co-authored this work I think I have the right to a copy. I was the graduate student Francis was working with.
1) The study investigated the effect of adding zirconium oxide nanoparticles to carbon black electrode materials on surface morphology and electrochemical performance.
2) Scanning electron microscopy showed that adding nanoparticles partially filled gaps between carbon black particles, increasing the specific surface area available for charge storage.
3) Electrochemical analysis found that increasing nanoparticle content initially increased total charge storage due to higher surface area and pseudocapacitive charge storage, but further increases reduced performance due to higher electrode resistance.
Magnetic and Chemical Order in Heusler Alloys Containing Neodymium and Moiybd...IJERA Editor
Saturation magnetization X-ray and neutron diffraction measurements have been made on alloys at the
compositions Nd2MoCd’, Nd2MoZn’, Nd2MoCu, Nd2MoTi, Nd2MoAg, Nd2MoZr and NdMoZr. The alloys
containing Cu and Ag have fully ordered Heusler, L21, Chemical structure. Nd2MoCd is similarly ordered but
with some partial Mo-Cd disorder. The alloys Nd2MoZn and Nd2MoTi each contain a secondary phase in
addition to the primary Heusler phase Nd2MoZr contains the two phases Nd122MoZr and Nd and NdMoZr is
ordered in the Clb structure. The alloys containing the group IIIB or IVB elements Cd, Zn, Cu, Ti or Ag are
ferromagnetically ordered, with the magnetic moment associated with the ordered Nd sites. The two alloys
containing the group VB elements Zr have vacant chemically ordered ‘Nd’ sites but are paramagnetic.
Effect of sodium doping on thermal properties of perovskite r mn o3 for poten...Alexander Decker
This document discusses the effect of sodium doping on the thermal properties of perovskite rare earth manganites RMnO3 for potential magnetoelectric applications. It studies the thermal, elastic, and cohesive properties of sodium-doped rare earth manganites R1-xNaxMnO3 (R3+ = La, Pr, Tb) using a modified rigid ion model and atom in molecules theory. It finds that sodium doping increases the A-site cation radius, affecting properties like lattice specific heat, Debye temperature, thermal expansion, bulk modulus, and cohesive energy. These thermal properties are important for determining the compatibility of components in thermoelectric devices and revealing electron-lattice coupling in
This document presents an interaction model to describe dipolar and superexchange interactions in cobalt-doped titanium dioxide thin films. It describes the relevant energy terms in the Hamiltonian, including Zeeman, crystalline anisotropy, dipolar interaction, and effective exchange energies. Simulation results using a Metropolis algorithm show magnetization curves as a function of temperature and field that resemble paramagnetic behavior but do not follow Curie-Weiss law. Zero-field cooled and field cooled magnetization curves are also presented from the simulations.
Ferroelectric nanostructures and their processing issues♪♫•*¨ *•.¸¸
This document discusses ferroelectric nanostructures and their processing issues. It covers several topics including important events in the history of ferroelectricity, factors that influence ferroelectric properties at the nanoscale, and different invasive and non-invasive approaches for processing ferroelectric nanostructures such as top-down methods like focused ion beam patterning and bottom-up methods like self-assembly. Potential applications of ferroelectric nanostructures are also mentioned, including data storage, piezoelectric actuators, and pyroelectric detectors.
The document discusses colossal magnetoresistance (CMR), where the electrical resistance of certain materials changes dramatically with an applied magnetic field. CMR was first observed in mixed-valence manganite materials and is caused by interactions between the electron spin, orbit, and lattice structure. Potential applications include smaller, higher capacity data storage devices. CMR remains an active area of research in physics and materials science due to its fundamental complexity and technological promise.
This document discusses theoretical and experimental studies on viologen-containing 1,1'-binaphthyls as potential near-infrared chiroptically switching materials. Theoretical modeling was used to correlate chiroptical properties with molecular geometry, showing maximal properties for a twisting angle of 60° and interchromophoric distance of 3.9 nm. Two chiral molecules containing viologen groups attached to a 1,1'-binaphthyl core through short spacers were synthesized and showed strong circular dichroism bands in the visible and near-infrared regions upon electrochemical reduction, demonstrating their potential as chiroptical switches. The cyclic molecule showed stronger chiroptical properties than the open-ring analogue.
Electronic structure of strongly correlated materials Part III V.AnisimovABDERRAHMANE REGGAD
This document discusses results from DFT+DMFT calculations on various strongly correlated materials. It summarizes calculations showing a strongly correlated metal state in SrVO3 with a lower Hubbard band, a Mott insulator transition in V2O3 accompanied by a small structural change, and heavy fermion behavior in Li2VO4 without f-electrons. It also discusses calculations of the charge transfer insulator NiO, pressure-induced transitions in MnO and Fe2O3, correlated covalent insulators FeSi and FeSb2, superconductivity in LaOFeAs, Jahn-Teller distortions and orbital ordering in KCuF3, and f-electron localization in cerium. The document
Ultrafast response of metal-semiconductor hybrid.pptxSabinaGurung12
This thesis presents an extensive study of self-organizatized synthesis of hybrid
nanostructure and their characterization using a combination of spectroscopic and microscopic
techniques, supported by theoretical modelling. Apart from the various potential applications of the
hybrid nanostructures reported, this thesis also provides an insight on the synergistic interaction
between Ag NP and CdTe QD. The future interest of this work involves utilization of these hybrid
nanostructure colloid for various applications like in optoelectronics and solar cells by transforming
the colloidal sample into thin films.
This document discusses the effect of heating rate on the structural and optical properties of silicon and magnesium co-doped zirconia nanopowders prepared by a sol-gel method. X-ray diffraction analysis showed that different heating rates between 1-10°C/min affected the formation of tetragonal and cubic phases, crystallinity, and particle size. Ultraviolet-visible spectroscopy showed that the band gap energy of the doped zirconia crystals decreased depending on the heating rate, with a minimum band gap of around 3-3.2 eV.
This document discusses simulating UV-vis spectra of methyl viologen and its radical cation using time-dependent density functional theory (TD-DFT). It optimizes the geometries of methyl viologen and its radical cation using DFT and discusses using TD-DFT with a 6-311G** basis set to simulate the UV-vis spectra. It also plans to simulate the UV-vis spectra using a multi-reference method called CASPT2.
The document discusses Crystal Field Theory, which explains the bonding in transition metal complexes. It describes how the electrostatic interaction between ligand electrons and metal d-orbitals results in a splitting of the d-orbital energies. In an octahedral field, the t2g orbitals are stabilized more than the eg orbitals. Crystal Field Theory can explain properties like electronic spectra, magnetic moments, and color of complexes. The magnitude of splitting depends on factors like the metal ion, its charge, the ligands, and can be represented by the crystal field splitting energy Δo.
Synthesis and charaterization of la1 x srxmno3 perovskite nanoparticlesMai Trần
In recent times perovskite materials are extensively studied and have attracted much attention because they exhibit interesting the properties, showing potential applications in commercial, technical and biomedical. In Vietnam, perovskite materials be of interest research and applications are strong but with major research direction is to go deep into the electrical properties and the magnetic properties. The Lanthanum Strontium manganite is a perovskite-based crystal-structured ceramic material with the formula of La1-xSrxMnO3, where x describes the doping ratio. It has attracted much attention due to its good magnetic, electrical, and catalytic properties and is becoming an attractive possibility material in several biomedical applications, particularly with nano-size. In industry, this material is commonly used in as a cathode material in commercially produced solid oxide fuel cells. In this thesis, we present the Perovskite nanoparticles La1-xSrxMnO3 were successfully synthesized of the nanosize La1-xSrxMnO3 at x = 0; 0.1; 0.2; 0.3 and 0.4 which prepared by a modified sol-gel method. Structure and magnetic properties of them were systematically investigated in dependence on doped Sr ratio x. The structure was investigated by XRD and show slightly changed but magnetic properties varied strongly with changing the doping ratio x. Magnetic properties of samples were studied by Vibrating Sample Mode of Physical Properties Measurement System show at the room temperature, the samples show superparamagnetic properties with high saturated magnetization MS of 57 emu/g which strongly dependents on the doped Sr ratio x.
This document discusses theoretical atomic and molecular physics research being conducted on recombination lines in nebulae spectra. The research group is investigating two recombination processes, radiative and dielectronic recombination, using atomic structure and R-matrix codes. They are studying carbon and magnesium ions to analyze planetary nebulae and draw conclusions about nebula conditions and compositions.
Coordination Compounds - CHARACTERIZATION AND OVERVIEW, DETECTION OF COMPLEX FORMATION, Formation of precipitate, Conductivity measurements , Change in chemical behaviour, Spectral methods, Magnetic Method, Spectral Calculations, Term symbols, Mulliken term symbols, Orgel diagrams - d1 configuration in Oh environment , d9 configuration in Oh environment, d1 configuration in Oh environment, Limitations Tanabe sugano diagrams, d2 configuration in Oh environment , Advantages over Orgel’s, Racah parameters
The document summarizes the metal-insulator transition in VO2, which occurs at 340K. In the metallic phase, VO2 exhibits bad metal behavior with short electron mean free paths. The insulating phase has two possible structures - M1 and M2. M1 involves pairing of V atoms and splitting of orbitals. M2 involves formation of zig-zag V chains. The transition may involve both Mott-Hubbard localization and a Peierls instability driven by soft phonon modes near the R point of the Brillouin zone. Precise values are estimated for the electronic parameters characterizing the insulating M1 phase, including Hubbard U, spin gap Δσ, and charge gap Δρ.
Similar to salerno-2-asus-170124105324_OCR.pdf (20)
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
The webinar may also give some examples on how nonprofits can best leverage Walmart Business+.
The event will cover the following::
Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analytics” feature, special discounts, deals and tax-exempt shopping.
Special TechSoup offer for a free 180 days membership, and up to $150 in discounts on eligible orders.
Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
Temple of Asclepius in Thrace. Excavation resultsKrassimira Luka
The temple and the sanctuary around were dedicated to Asklepios Zmidrenus. This name has been known since 1875 when an inscription dedicated to him was discovered in Rome. The inscription is dated in 227 AD and was left by soldiers originating from the city of Philippopolis (modern Plovdiv).
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
The chapter Lifelines of National Economy in Class 10 Geography focuses on the various modes of transportation and communication that play a vital role in the economic development of a country. These lifelines are crucial for the movement of goods, services, and people, thereby connecting different regions and promoting economic activities.
This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
1. Electronic structure of strongly
correlated materiais
Part II
Vladimir I. Anisimov
Institute of Metal Physics
Ekaterinburg, Rússia
2. LDA+U method applications
• Mott insulators
• Charge order: Fe3O4
• Spin order: calculation of exchange interaction
parameters in CaVnO2n+1
• Orbital order: KCuF3, LaMnO3
• Charge and orbital order: Pr0.5Ca0.5MnO3
• Low-spin to high-spin transition:Co+3 in LaCoO3
• Stripe phase of cuprates
3. LDA+U method applications
Mott insulators that are small gap semiconductors
or even metals in LSDA are correctly reproduced in LDA+U
as wide gap magnetic insulators with well localized d-electrons
V.Anisimov et al, Phys.Rev. B 44, 943 (1991)
4. LDA+U method applications
The density of states for ferromagnetic Gd
metal from LDA+U calculation and results
of BIS (bremsstrahlung isochromat
spectroscopy) and XPS (x-ray
photoemission spectroscopy) experiments.
Antiferromagnetic Mott insulator
CaCuO2 (in LDA nonmagnetic metal)
5. Charge order in Fe3O4
half of the octahedral positions is occupied by Fe+3 and other half by Fe+2.
V.Anisimov et al, Phys. Rev.B 54, 4387 (1996)
Fe3O4 has spinel
crystal structure
one Fe+3 ion in tetrahedral position (A)
two Fe+2.5 ions in octahedral positions (B)
Below TV=122K a charge ordering happens Verwey transition
Simultaneous metal-insulator transition:
6. LDA and charge order problem
;
n
U
)
n
n
(
;
n
U
)
n
n
(
;
dn
d
U 0
0
LSDA
2
0
0
LSDA
1
Charge disproportionation in LSDA is unstable due to self-interaction problem
in LDA+U self-interaction is explicitly canceled
)
n
2
1
(
U
))
n
n
(
2
1
(
U
)
n
n
(
)
n
2
1
(
U
))
n
n
(
2
1
(
U
)
n
n
(
0
0
0
0
LSDA
2
2
0
0
0
0
LSDA
1
1
8. Fe3O4
Charge and orbital order
in experimental low-
temperature monoclinic
crystal structure Fe3O4
I.Leonov et al,
PRL93,146404 (2004)
9. Fe3O4
Charge and orbital order in experimental low-temperature
monoclinic crystal structure Fe3O4
10. Exchange interactions in layered vanadates
• n=3: CaV3O7 has unusual long-range spin order
• n=4: CaV4O9 is a frustrated (plaquets) system with a spin gap value 107K
• n=2: CaV2O5 is a set of weakly coupled dimers with a large spin gap 616 K
• isostructural MgV2O5 has very small spin gap value < 10K
V.Anisimov et al, Phys.Rev.Lett. 83, 1387 (1999)
Fully ab-initio description of magnetic properties
LDA+U calculations:
eigenfunctions and
eigenvalues
Exchange couplings
calculations using
LDA+U results
Heisenberg
model is solved
by QMC
CaVnO2n+1 (n=2,3,4) systems show a large variety of magnetic properties:
11. Crystal structure and orbitals
V+4 ions in d1 configuration.
Oxygen atoms form pyramids with V atoms inside them.
Crystal structure of CaVnO2n+1
is formed by VO5 pyramids
connected into layers.
The occupied dxy-orbital of V+4 ions in CaV3O7
12. Exchange couplings scheme
V atoms represented by large circles with different colors have different z-coordinate
Oxygen atoms are shown by small circles
Long range magnetic structure of CaV3O7 is depicted by white arrows
The basic crystal structure and the notation of exchange couplings in
CaV2O5 and MgV2O5 CaV3O7 CaV4O9
13. QMC solution of Heisenberg model
Comparison of the calculated and measured susceptibility
14. Orbital order in KCuF3
with Jahn-Teller distorted CuF6 octahedra.
KCuF3 has cubic perovskite
crystal structure
15. Orbital order in KCuF3
hole density of the same symmetry
A.Lichtenstein et al, Phys. Rev.B 52, R5467 (1995); J.Medvedeva et al, PRB 65,172413 (2002)
In KCuF3 Cu+2 ion has
d9 configuration
with a single hole in eg doubly degenerate subshell.
Experimental crystal structure
antiferro-orbital order
LDA+U calculations for undistorted
perovskite structure
16. Cooperative Jahn-Teller distortions in KCuF3
LSDA gave cubic perovskite crystal
structure stable in respect to Jahn-
Teller distortion of CuF6 octahedra
Only LDA+U produces
total energy minimum
for distorted structure
Calculated
exchange couplings:
c-axis 17.5 meV
ab-plane –0.2 meV
One-dimensional
antiferromagnet
17. Orbital order in Pr1-xCaxMnO3 (x=0 and 0.5)
Orbital order for partially filled eg shell
of Mn+3 ion in PrMnO3 in a crystal structure
without JT-distortion from LDA+U
with tilted and rotated Jahn-Teller distorted MnO6 octahedra.
PrMnO3 has orthorhombic perovskite crystal structure
18. Pr0.5Ca0.5MnO3
experimental magnetic and
charge-orbital order
Orbital order for partially filled eg shell
of Mn+3 ion in Pr0.5Mn0.5O3 in a crystal structure
without JT-distortion from LDA+U
V.Anisimov et al, Phys.Rev.B 55, 15 494 (1997); M.Korotin, PRB62, 5696 (2000)
19. Spin state of Co+3 in LaCoO3
3d-level scheme for
low-spin ground state
Open circle denotes a hole in oxygen p-shell.
Scheme representation of various
Co d6+d7L configurations in
different spin states:
low intermediate high
M.Korotin et al, Phys.Rev.B 54 (1996) 5309; I.Nekrasov et al, Phys. Rev. B 68, 235113 (2003)
20. Spin state of Co+3 in LaCoO3
relative to the energy of t2
6
geg
0 state versus R3c lattice constant.
The total energies for various spin states of LaCoO3
21. HoCoO3 versus LaCoO3
The rhombohedral crystal structure of LaCoO3 (left) and the orthorhombic
crystal structure of HoCoO3 (right). Co - large spheres; O - small spheres.
22. HoCoO3 versus LaCoO3
Comparison of total energy per Co ion of intermediate and low-spin state
solutions for LaCoO3 and HoCoO3 calculated with the LDA+U approach
as a functions of temperature. The temperature of transition is calculated
as the temperature where two lines cross.
I. A. Nekrasov et al, PRB 68, 235113 (2003)
23. Stripe phase in cuprates (La7/8Sr1/8CuO4)
V.Anisimov et al, Phys. Rev. B 70, 172501 (2004)
26. Other LDA+U results
• Magnetic transition in FeSi1–xGex
(PRL 76 (1996) 1735; PRL 89, 257203 (2002)
• Exchange couplings in molecular magnet Mn-12
([Mn12O12(CH3COO)16(H2O)4]2CH3COOH4H2O )
(PRB 65, 184435 (2002 ))
• Insulating ground state of quarter-filled ladder
NaV2O5 (PRB 66, 081104 (2002) )
• CrO2 : a self-doped double exchange ferromagnet
(PRL 80, 4305 (1998) )
• Mott-Hubbard insulator on Si-terminated SiC(0001)
surface (PRB 61, 1752 (2000))
• Polaron effects in La2-xSrxCuO4 and La2-xSrxNiO4
(PRL 68, 345 (1992);PRB 55,12829 (1997); PRB 66, 100502 (2002))
• Antiferromagnetism in linear-chain Ni compound
[Ni(C6H14N2)2] [Ni(C6H14N2)2Cl2]Cl4 (PRB 52,6975 (1995) )
27. LDA+DMFT
LDA+U
Static mean-field approximation
Energy-independent potential
|
|
ˆ
m
inl
V
inlm
V
m
m
m
m
LDA+DMFT
Dynamic mean-field approximation
Energy-dependent complex
self-energy operator
|
)
(
|
)
(
ˆ
m
inl
inlm
m
m
m
m
Applications:
Insulators with long-range
spin-,orbital- and charge order
Applications:
Paramagnetic, paraorbital
strongly correlated metals
Unsolved problem: short
range spin and orbital order
Dynamical cluster approximation (DCA)
28. Dynamical Mean-Field Theory
Object of investigation: interacting
lattice fermions dynamics
Simplest description – Hubbard
model
Correlations:
Square lattice, z=4
†
, ,
i j i j
i j i
H t c c U n n
i j i j
n n n n
•Approximations need to be made
29. Dynamical Mean-Field Theory
Lattice problem is replaced by effective impurity problem with
complex energy dependent potential (self-energy) on all
lattice sites except distinguished one
30. Dynamical Mean-Field Theory
Metzner, Vollhardt (1989)
d→∞
Georges, Kotliar (1992)
mapping onto impurity problem,
self-consistent equations
Real lattice Effective impurity problem
Mapping
k
k
G t
1
G
2
k
k k
V
31. Dynamical Mean-Field Theory
Approximation: electron self-energy is local and does not depend
on momentum (wave vector) k but only on frequency iωn:
Lattice Green function is defined by self-energy:
Hybridization of the site orbitals with the rest of the crystal in effective single
impurity model is described by hybridization function (iωn) or non-interacting
bath Green function G0(iωn):
32. Dynamical Mean-Field Theory
The DMFT mapping means:
Dyson equation for impurity problem:
Dyson equation is used twice in DMFT. First for known self-energy and lattice
Green function bath Green function is calculated:
Then after impurity problem solution new approximation for self-energy can be defined:
33. DFT+DMFT calculations scheme
Local Green function:
Dyson equation defines bath Green function:
Self-consistent condition:
Impurity problem defined by bath Green
function is solved by QMC
34. DMFT calculations scheme
Impurity solvers:
•Quantum Monte Carlo method (QMC) – exact and efficient
but very computer time consuming
•Numerical renormalization group (NRG) – unpractical for orbital
degeneracy > 2
•Exact diagonalization method (ED) – discrete spectra and not
suitable for orbital degenerate problem
•Iterative Perturbation Theory (IPT) – interpolation approximation
•Non-crossing Approximation (NCA)- first terms of hybridization
expansion series
35. DMFT calculations scheme
Quantum Monte Carlo method (QMC)
discrete Hubbard-Stratonovich transformation:
Product n↑n↓ can be rewritten as a sum of quadratic and linear terms:
int
H
e
Evolution operator can be linearized by
36. DMFT calculations scheme
Quantum Monte Carlo method (QMC)
where parameter :
discrete field s is an Ising-like variable taking the values +1 and -1
Partition function
the imaginary time interval is discretized into L time slices:
37. DMFT calculations scheme
Quantum Monte Carlo method (QMC)
Using Hubbard-Stratonovich transformation:
and partition function becomes a sum over Ising fields sl :
40. DMFT calculations scheme
Quantum Monte Carlo method (QMC)
the total number of all possible spin configurations {sl} = s1, . . . , sL
for which one should calculate G(τ ) is equal to 2L (≈ 2100 ≈ 1030).
Many-dimensional integrals can be calculated by statistical Monte Carlo method.
Stochastically generated points in many-dimensional space xi are accepted
to be included in summation with probability proportional to
41. DMFT calculations scheme
Quantum Monte Carlo method (QMC)
probability P is proportional to
physical Greens function is then given as an average of
Probability of acceptance P{s}→{s′} for new configuration {s′}
obtained from {s} is calculated according to Metropolis formula:
42. DMFT calculations scheme
Quantum Monte Carlo method (QMC)
The Markov process is realized by going from configuration s to configuration
s′ by a single spin flip sp = −sp with probability of acceptance
P{s}→{s′} for new configuration {s′} obtained from {s}
Markov chain is given by every accepted configuration:
instead of summation with weights Zs1,...,sL an averaging of gσ
s1,...,sL(τl, τl′ )
over all accepted configuration is performed because probability
of acceptance is proportional to Zs1,...,sL.
Number of Markov chain “sweeps” is usually ≈ 106 that is much smaller then
total configurations number 2L (≈ 2100 ≈ 1030).
43. DMFT calculations scheme
Total energy calculation in LDA + DMFT
where ELDA is total energy obtained in LDA calculation, EDMFT is an energy calculated
in DMFT and EMF is an energy corresponding to static mean-field approximation
(restricted Hartree-Fock) for the same Hamiltonian as used in DMFT calculations.
44. DMFT calculations scheme
Total energy calculation in LDA + DMFT
where Gk(iωn) is electronic Green function corresponding to wave vector k
The average values for particle number operators products
<nilmσ nilm′σ> can be calculated directly in QMC method
Energy corresponding to static mean-filed approximation EMF is calculated
analogously with replacing interacting Green function Gk(iωn) on
GLDA
k (iωn) calculated with LDA Hamiltonian:
45. DMFT calculations scheme
Total energy calculation in LDA + DMFT
where nd is a total correlated electrons number on the site id
and U is an average value of Coulomb interaction between different orbitals.
and also with replacing second term in EDMFT on
Coulomb interaction energy in the following form:
46. DMFT calculations scheme
Maximum entropy method for analytical continuation on real energies
QMC calculation procedure results in Matsubara Green function G(τ ) for
discrete imaginary time points τl − τl′ or imaginary energies G(iωn). Spectral
function A(ω) for real energies ω is solution of integral equation:
Entropy maximization principle accounts for stochastic noise in QMC Green function
47. DFT+DMFT calculations scheme
Calculation scheme of
Σ – Self-energy
G – Green function
U – Coulomb interaction
EWF – Energy of WF
QWF – Occupancy of WF
M(i) – Moments
V – DFT potential
V.Anisimov et al, Phys. Rev. B 71, 125119 (2005).
48.
k
i
k
G 1
)
)
(
(
)
(
Dynamical Mean-Field Theory
k
k
G 1
))
(
)
(
(
)
(
Spectral function and self-energy
49. Dynamical Mean-Field Theory
Three peak spectral function and metal insulator transition in DMFT
A. Georges et al, Rev. Mod. Phys 68, 13 (1996)
50. Dynamical Mean-Field Theory
Three peak spectral function and metal insulator transition in DMFT
R. Bulla et al, Phys. Rev. B 64, 045103 (2001)
51. Dynamical Mean-Field Theory
Temperature dependence of quasiparticle peak in DMFT
Half-filling 0.03 hole doping
Th. Pruschke et al, Phys. Rev. B 47, 3553 (1993)
52. Dynamical Mean-Field Theory
Suppression of correlation
strength and spectral weight
transfer between Hubbard
bands with hole doping in
non-degenerate Hubbard model
H. Kajueter et al, Phys. Rev. B 53, 16 214 (1996)
53. Dynamical Mean-Field Theory
Orbital degeneracy dependence of quasiparticle peak in DMFT
Half-filling n=0.9
J. E. Han et al, Phys. Rev. B 58, R4199 (1998)
54. Dynamical Mean-Field Theory
Orbital degeneracy dependence of quasiparticle peak in DMFT
Triply degenerate band
P. Lombardo et al, Phys. Rev. B 72, 245115 (2005)