Renormalization from Density Functional Theory to Strong Coupling Models for the Electronic Structure of La2CuO4

1989 ◽  
Vol 169 ◽  
Author(s):  
Mark S. Hybertsen ◽  
Michael Schluter ◽  
E.B. Stechel ◽  
D.R. Jennison
Keyword(s):  
Electronic Structure ◽  
Hubbard Model ◽  
Strong Coupling ◽  
Density Functional ◽  
Nearest Neighbor ◽  
Quantitative Agreement ◽  
Energy Scale ◽  
Low Energy ◽  
Energy Spectra ◽  
Functional Theory

AbstractStrong coupling models for the electronic structure of La2CuO4 are derived in two successive stages of renormalization. First, a three-band Hubbard model is derived using a constrained density functional approach. Second, exact diagonalization studies of finite clusters within the three band Hubbard model are used to select and map the low energy spectra onto effective one-band Hamiltonians. At each stage, some observables are calculated and found to be in quantitative agreement with experiment. The final results suggest the following models to be adequate descriptions of the low energy scale dynamics: (1) a spin 1/2 Heisenberg model for the insulating case with nearest neighbor J≈130 meV; (2) a "t–t'–J" model with nearly identical parameters for the electron and hole doped cases.

Investigated electronic structure and magnetic ordering of rare earth impurities (Eu, Gd) in ZnO

2016 ◽  
Vol 30 (31) ◽  
pp. 1650225 ◽  
Author(s):  
F. Benosman ◽  
Z. Dridi ◽  
Y. Al-Douri ◽  
B. Bouhafs
Keyword(s):  
Electronic Structure ◽  
Rare Earth ◽  
Density Functional ◽  
Nearest Neighbor ◽  
Magnetic Coupling ◽  
Magnetic Ordering ◽  
Hole Doping ◽  
High Electron ◽  
Functional Theory ◽  
Good Agreement

First-principles calculations of the electronic structure of substitutional rare earth (RE) impurity (Eu and Gd) in wurtzite ZnO have been performed using density functional theory within a Hubbard potential correction to the RE 4f states. For Eu-doped ZnO, the magnetic coupling between Eu ions in the nearest neighbor sites is ferromagnetic (FM). The room temperature (RT) ferromagnetism (FM) can be enhanced by an appropriate hole doping into the sample. The ZnO:Gd is found to favor the antiferromagnetic (AFM) phase. The FM can be achieved by high electron doping. The native defects effect (V[Formula: see text], V[Formula: see text]) on the FM is also studied. The oxygen vacancies seem to play an important role in the generation of the FM in both ZnO:Eu and ZnO:Gd, which is in good agreement with recent experimental results.

Electronic Structure of Metallophthalocyanines, MPc (M = Fe, Co, Ni, Cu, Zn, Mg) and Fluorinated MPc

2020 ◽  
Author(s):  
Qunfei Zhou ◽  
Zhen-Fei Liu ◽  
Tobin J. Marks ◽  
Pierre Darancet
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Organometallic Compounds ◽  
Optical Excitation ◽  
Quantitative Agreement ◽  
Excitation Energies ◽  
Functional Theory ◽  
Metal Phthalocyanines ◽  
Optical Band Gaps ◽  
Experimental Values

<p>We compute the electronic structure and optical excitation energies of metal-free and transition metal phthalocyanines (H2Pc and MPc for M = Fe, Co, Ni, Cu, Zn, Mg) using density functional</p><p>theory with optimally-tuned range-separated hybrid functionals (OT-RSH).We show that the OT-RSH approach provides photoemission spectra in quantitative agreement with experiments</p><p>as well as optical band gaps within 10% of their experimental values, capturing the interplay of localized d-states and delocalized pi-pi* states for these organometallic compounds. We examine the tunability of MPcs and H2Pc through fluorination, resulting in quasi-rigid shifts of the molecular orbital energies by up to about 0.7 eV. Our comprehensive dataset provides a new computational benchmark for phthalocyanines molecules, significantly improving upon other density-functional-theory-based approaches.</p>

Electronic Structure of Metallophthalocyanines, MPc (M = Fe, Co, Ni, Cu, Zn, Mg) and Fluorinated MPc

2020 ◽  
Author(s):  
Qunfei Zhou ◽  
Zhen-Fei Liu ◽  
Tobin J. Marks ◽  
Pierre Darancet
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Organometallic Compounds ◽  
Optical Excitation ◽  
Quantitative Agreement ◽  
Excitation Energies ◽  
Functional Theory ◽  
Metal Phthalocyanines ◽  
Optical Band Gaps ◽  
Experimental Values

<p>We compute the electronic structure and optical excitation energies of metal-free and transition metal phthalocyanines (H2Pc and MPc for M = Fe, Co, Ni, Cu, Zn, Mg) using density functional</p><p>theory with optimally-tuned range-separated hybrid functionals (OT-RSH).We show that the OT-RSH approach provides photoemission spectra in quantitative agreement with experiments</p><p>as well as optical band gaps within 10% of their experimental values, capturing the interplay of localized d-states and delocalized pi-pi* states for these organometallic compounds. We examine the tunability of MPcs and H2Pc through fluorination, resulting in quasi-rigid shifts of the molecular orbital energies by up to about 0.7 eV. Our comprehensive dataset provides a new computational benchmark for phthalocyanines molecules, significantly improving upon other density-functional-theory-based approaches.</p>

Doping effects on the geometric and electronic structure of tin clusters

2019 ◽  
Vol 21 (44) ◽  
pp. 24478-24488 ◽  
Author(s):  
Martin Gleditzsch ◽  
Marc Jäger ◽  
Lukáš F. Pašteka ◽  
Armin Shayeghi ◽  
Rolf Schäfer
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Beam Deflection ◽  
Functional Theory ◽  
Doping Effects ◽  
Depth Analysis ◽  
Trajectory Simulations

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.

Exchange-Correlation Energy Densities and Response Potentials: Connection Between Two Definitions and Analytical Model for the Strong-Coupling Limit of a Stretched Bond

2019 ◽  
Author(s):  
S. Giarrusso ◽  
Paola Gori-Giorgi
Keyword(s):  
Density Functional Theory ◽  
Strong Coupling ◽  
Density Functional ◽  
Correlation Energy ◽  
Order Term ◽  
Strong Coupling Limit ◽  
Local Form ◽  
Coupling Constant ◽  
Functional Theory ◽  
Exchange Correlation

We analyze in depth two widely used definitions (from the theory of conditional probablity amplitudes and from the adiabatic connection formalism) of the exchange-correlation energy density and of the response potential of Kohn-Sham density functional theory. We introduce a local form of the coupling-constant-dependent Hohenberg-Kohn functional, showing that the difference between the two definitions is due to a corresponding local first-order term in the coupling constant, which disappears globally (when integrated over all space), but not locally. We also design an analytic representation for the response potential in the strong-coupling limit of density functional theory for a model single stretched bond.<br>

scholarly journals Complex magnetism of the two-dimensional antiferromagnetic Ge2F: from a Néel spin-texture to a potential antiferromagnetic skyrmion

RSC Advances ◽  
2021 ◽  
Vol 11 (15) ◽  
pp. 8654-8663
Author(s):  
Fatima Zahra Ramadan ◽  
Flaviano José dos Santos ◽  
Lalla Btissam Drissi ◽  
Samir Lounis
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Density Functional ◽  
Low Energy ◽  
Two Dimensional ◽  
Functional Theory ◽  
2D Material ◽  
Energy Models ◽  
Spin Texture

Based on density functional theory combined with low-energy models, we explore the magnetic properties of a hybrid atomic-thick two-dimensional (2D) material made of germanene doped with fluorine atoms in a half-fluorinated configuration (Ge2F).

scholarly journals Influence of Copper(I) Halides on the Reactivity of Aliphatic Carbodiimides

2020 ◽  
Vol 3 (1) ◽  
pp. 20
Author(s):  
Valentina Ferraro ◽  
Marco Bortoluzzi
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
General Formula ◽  
Electron Density ◽  
Density Functional ◽  
Functional Theory ◽  
Fukui Functions ◽  
Bond Lengths ◽  
Linear Complexes ◽  
Nitrogen Bond

The influence of copper(I) halides CuX (X = Cl, Br, I) on the electronic structure of N,N′-diisopropylcarbodiimide (DICDI) and N,N′-dicyclohexylcarbodiimide (DCC) was investigated by means of computational DFT (density functional theory) methods. The coordination of the considered carbodiimides occurs by one of the nitrogen atoms, with the formation of linear complexes having a general formula of [CuX(carbodiimide)]. Besides varying the carbon–nitrogen bond lengths, the thermodynamically favourable interaction with Cu(I) reduces the electron density on the carbodiimides and alters the energies of the (NCN)-centred, unoccupied orbitals. A small dependence of these effects on the choice of the halide was observable. The computed Fukui functions suggested negligible interaction of Cu(I) with incoming nucleophiles, and the reactivity of carbodiimides was altered by coordination mainly because of the increased electrophilicity of the {NCN} fragments.

scholarly journals Comparison of the Performances of Different Computational Methods to Calculate the Electrochemical Stability of Selected Ionic Liquids

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3221
Author(s):  
Annalisa Paolone ◽  
Sergio Brutti
Keyword(s):  
Ionic Liquids ◽  
Density Functional ◽  
Quantitative Agreement ◽  
Electrochemical Stability ◽  
Functional Theory ◽  
Molecular Systems ◽  
Reduction Potentials ◽  
Adiabatic Transitions ◽  
Alkyl Ammonium ◽  
Transition Scheme

The electrochemical stability windows (ESW) of selected ionic liquids have been calculated by comparing different computational approaches previously suggested in the literature. The molecular systems under study are based on di-alkyl imidazolium and tetra-alkyl ammonium cations coupled with two different imide anions (namely, bis-fluorosulfonyl imide and bis-trifluoromethyl sulfonyl imide), for which an experimental investigation of the ESW is available. Thermodynamic oxidation and reduction potentials have here been estimated by different models based on calculations either on single ions or on ionic couples. Various Density Functional Theory (DFT) functionals (MP2, B3LYP, B3LYP including a polarizable medium and empirical dispersion forces) were exploited. Both vertical and adiabatic transitions between the starting states and the oxidized or reduced states were considered. The approach based on calculations on ionic couples is not able to reproduce the experimental data, whatever the used DFT functional. The best quantitative agreement is obtained by calculations on single ions when the MP2 functional in vacuum is considered and the transitions between differently charged states are vertical (purely electronic without the relaxation of the structure). The B3LYP functional underestimates the ESW. The inclusion of a polar medium excessively widens the ESW, while a large shrinkage of the ESW is obtained by adopting an adiabatic transition scheme instead of a vertical transition one.

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