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Questions tagged [hubbard-model]

For questions about (or related to) the Hubbard model.

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Issue with hp.x Quantum ESPRESSO Calculation on HPC System

I am trying to run an hp.x Quantum ESPRESSO calculation on an HPC system, but the output is not as expected. The scf calculation runs without any issues. However, ...
Camilla's user avatar
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1 vote
0 answers
20 views

How to efficiently calculate Hubbard parameters using hp.x for isolated dopant?

Background I know how to use hp.x in case of undoped periodic system. We take a small unit cell, apply some initial guess values to obtain the ground state (pw.x), and then run the hp.x on top of it ...
Abdul Muhaymin -Free Palestine's user avatar
4 votes
0 answers
57 views

Algorithm to find phase boundaries

I am looking for an algorithm/library to find phase boundaries as a function of some parameters. E.g. in the Hubbard model, the phase diagram as a function of U and doping hosts metal/insulator ...
Tyler Sterling's user avatar
4 votes
0 answers
82 views

DFT+U: localizing electrons on combination of atomic orbitals

TLDR: DFT+U is a cheap scheme to help localize electrons on atomic orbitals by penalizing fractional occupancies of such orbitals. However, when one tries to localize an electron/hole on an atomic ...
Barbaud Julien's user avatar
5 votes
1 answer
90 views

Is it necessary to use DFT+U when calculating binding energy?

Recently I am trying to calculate the binding energy between CO2/ C2H2 and MOF (containing Ni, C, H, O, N). I want to know that do I have to use DFT+U for Ni element in this binding energy calculation?...
Tieyuan Bian's user avatar
6 votes
1 answer
112 views

could meta-GGA-r2scan descript d electron localization and polaron the same as Hybrid functional?

I notice that r2scan could be more accurate than rscan, but I am unsure if r2scan could describe the d electron localization without Hubbard+U? Or do I still need Hubbard+U with r2scan?
Jack's user avatar
  • 2,057
6 votes
0 answers
132 views

Eigenvalues of Hubbard occupancy matrix [closed]

I am studying Hematite (Fe2O3) Antiferromagnetic configuration using QE 7.0 (EDIT: compiled and tried 7.1) at the PBE+U level (U = 4.5). I obtained an excellent agreement with experimental data on ...
Nekkrad's user avatar
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2 votes
0 answers
50 views

What's the meaning of a Hubbard term determined by repeated investigation? [closed]

In the paper bellow they used GGA+U to investigate the structural, electronic and optical properties of Ag- and Cu-doped ZnO. https://www.emerald.com/insight/content/doi/10.1108/MI-05-2022-0088/full/...
Camilla's user avatar
  • 2,209
4 votes
0 answers
77 views

How to implement Ueff​=U−J in a Quantum ESPRESSO input file? [closed]

I want to implement Ueff​=U−J in a Quantum ESPRESSO input file, but I don't know how to do that. I found the following on the internet: ...
Camilla's user avatar
  • 2,209
2 votes
1 answer
610 views

Phonon Dispersion of SrTiO3, EuTiO3 using Quantum Espresso (DFT-U)

the last few days I've tried to calculate the phonon-dispersion of SrTiO3 (STO) and EuTiO3 (ETO) using the PHonon package of QE. SCF, DOS, PDOS and Bandsctructure calculation worked well on these ...
sAimen94's user avatar
4 votes
0 answers
204 views

The comparison of bandgap value of slab and bulk phase [closed]

I tried to calculate the bandgap of the TiO2-Rutile bulk phase, DFT(not +U) calculation shows the bandgap is about 1.8eV, which is roughly the same as the 1.78eV on the Material Project. When ...
Jack's user avatar
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9 votes
1 answer
257 views

In which conditions can the self-consistent Hubbard U value calculated using Quantum Espresso be used for other VASP calculations?

I have seen that some articles calculate Hubbard $U$ value self-consistently using Quantum Espresso code. Then, they use it in VASP calculations. My question is: In which conditions can this value be ...
Chi Kou's user avatar
  • 5,853
4 votes
1 answer
272 views

How to run hp.x command in Quantum ESPRESSO 6.8?

How to run hp.x command in QuantumEspresso v6.8? It is saying command not found. After doing ...
Priyanka Jha's user avatar
4 votes
1 answer
224 views

Hubbard model SU(2) symmetry: manifest invariance

Could someone explain, is it possible to make Hubbard Hamiltonian manifestly SU(2) invariant? I know about the interaction term, but how would kinetic (hopping effect) term have to look like? Here I'm ...
Bojan Obradovic's user avatar
6 votes
0 answers
1k views

How to use hp.x in Quantum ESPRESSO to calculate Hubbard parameter [closed]

I want to work with GGA +U on Quantum espresso to calculate the electronic properties of Ni Co co-doped ZnO system, but I can't figure out how to use the hp.x program for my system to calculate the ...
ismail benaicha's user avatar
12 votes
1 answer
747 views

How to calculate the potential in Hubbard-U correction and when to apply it?

I have seen that in certain cases Hubbard-U correction is relevant yet I have seen a number of papers that have not used it. So, I want to know if there is any theoretical basis for finding this ...
Ashique Lal's user avatar
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16 votes
1 answer
858 views

The Hund's J - Why can this be quantified?

I was reading on the implementation of Hubbard 'U' in Density Functional Theory. The Hubbard 'U' can be thought of as a parameter that accounts for the on-site electron-electron interactions in ...
livars98's user avatar
  • 2,506
22 votes
1 answer
276 views

Database or repository with values for the Hubbard potential U?

The Materials Project and other materials databases have a nice periodic table on their home page that allows you to search for compounds. For some materials, they give an empirical $U$ value used to ...
epalos's user avatar
  • 4,879
29 votes
3 answers
4k views

What is the appropriate way of determining a value for the Hubbard-like potential U for LDA+U / GGA+U calculations?

It is known that neither LDA or GGA correctly account for the strong on-site Coulomb interaction of localized electrons[1]. A cost-effective way of correcting this is by using a Hubbard-like term $U$. ...
epalos's user avatar
  • 4,879