Questions tagged [density-functional-theory]
For questions about simulations using Density Functional Theory.
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Carbon Capture Research - Force Constants & Basis Sets
Greetings Matter Modeling,
I'm researching carbon capture dynamics in the context of sorbent regeneration.
The UN IPCC Net-Zero goal requires 75 Mt-CO₂/year captured by 2030. According to the IEA, we ...
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Wrong lattice parameter of CeO2 after structure relaxation with VASP
I am calculating the lattice parameter of CeO2 with VASP, but the optimized lattice parameter is wrong according to many references (Physical Review B 75, 035109 (2007); The Journal of Chemical ...
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What (executable) command to calculate charge density using quantum espresso?
I'm trying to calculate the charge density of a structure using quantum espresso, I've already used the DENS.X and DEN.X commands, but in both tests the executable not found error appears. Can someone ...
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Error in TranSIESTA: "The electrode down-folding region is 0 in the device region"
When I run a tranSIESTA calculation, the SCF converges, and the TBtrans output shows the following error:
...
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Free energy calculation
I want to plot the relationship between free energy and temperature. I want to consider two plots, when phonons are considered and when phonons are not considered how the free energy changes with ...
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When do I use the lattice parameters obtained computationally vs experimentally?
I have been trying to simulate the properties of Bi2Se3. But the lattice parameters given in Materials Project (which I believe is obtained computationally) is inconsistent with that of experimental ...
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Strange change in total energy when lattice relaxing of EuTiO3 material and then atomic relaxing in a specific direction using Quantum Espresso
These days, I'm having a trouble in atomic relaxing of "EuTiO3" with tetragonal symmetry using Quantum espresso 7.1 for a period of more that a week. This material have a transverse optical ...
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Finding optical properties (epsilon) by Quantum ESPRESSO
I am calculating the dielectric ( Epsilon ) for ZnO by quantum espresso, when I run the eps.in file, I always get this error. ' Reading namelist energy_grid'
How do I solve this problem.
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Creating nanocomposite with material studio
I need to create ZnO/ graphene sheet nanocomposite with material studio and i dont know how. Please, help me or guide me to some one who can help me. I'm blocked.
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QE - transition state SCF not converging
Background
Using Quantum Espresso examining a porous material, that has a ligand with an aromatic group. The aim is to rotate the aromatic group and determine an energy profile for the rotation. The ...
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Why are my HPC calculations not running in SLURM?
Question
I submitted 2 jobs for the first time in a HPC to test it. It's a very light calculation that takes almost 5 minutes or less in my desktop. But it has been almost 1 hour since I submitted the ...
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Calculation of charge transport with the non-orthogonal basis Hamiltonian based on the non-equilibrium Green's function method
I am thinking about one question. If the Hamiltonian matrix is based on the non-orthogonal basis, how to compute the charge conductance with the Non-Equilibrium Green's Function (NEGF) method.
Suppose ...
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Bader charge calculation in Quantum ESPRESSO DFT
I am searching for calculating Bader charge using Quantum ESPRESSO. I am using pseudopotential based DFT calculation. And I have charge density files (cube and XSF formats).
My objective is to ...
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Constrained geometry optmization: Molecule interacts with its surroundings
I have a water cluster(suppose) generated from MD run. Now, I want to optimize the geometry of only one water molecule of interest using QC methods (e.g. B3LYP/6-31+G(d,p)). I intend that the water ...
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How to set the LMAXMIX tag in VASP for the material BaLaMn2O6?
I am trying to do DFT+U calculation for the material BaLaMn2O6 . As per the vaspwiki it is recommended to set LMAXMIX = 4 (d-elements) and ...
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How to perform atomistic spin dynamics (ASD) Ab Initio Molecular Dynamics (AIMD) using VASP?
I have tried normal AIMD simulation using VASP for Non magnetic materials. Now, I am interested to perform the molecular dynamics simulations for the finite temperature for Magnetic materials to ...
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Calculation of charge defect formation energy
I am confused about the calculation of the charge defect formation energy equation with these two terms (from figure below):
$\Delta V$: alignment term, and
$E_{corr}$: correlation term.
How can I ...
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Spin-orbit coupling and lattice constant
Cross-posted on Chem.SE.
Is there any evidence that spin-orbit coupling (SOC) leads to a crystal lattice distortion? Using Quantum Espresso and DFT, I am getting different relaxed lattice constants ...
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Is it possible to find H-bond enrgy with O-H distance less than 0.95A?
I am trying to calculate the energy of a hydrogen bond between RCOO- and Tyrosine (figure below). I freeze the O-O bond at 2.8A and calculate the energy by changing the distance between O-H. But when ...
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Can the the relaxed energy of a material system (eV/atom) computed by DFT using VASP be positive?
If it is positive, why is it so? Is it due to specific convergence criteria or choice of pseudopotentials? I cannot check the convergence of the DFT calculations as they have been downloaded from a ...
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Determining the Nature of a Material's Band Structure: Metallic or Semi-Metallic?
I have obtained a band structure plot (see image below) for a crystalline material. The Fermi level is set at the zero energy level. Based on the band structure, I am uncertain whether the material ...
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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 ...
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Calculation of formation energy of a nanotube using DFT
Suppose that we have a bulk structure of a two-dimensional (2D) material,.e.g graphite, and we want to construct a single-wall carbon nanotube tube starting from this bulk structure.
If we already ...
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Transiesta with siesta version 4.1.5 not converging
Good evening everyone,
With previous Transiesta versions, we would not have issues with finding the transport involving graphene. However, this was not the case with the latest version. We tried:
...
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Adsorption of Li on GeC (optimization problem)
Actually I am trying to study the adsorption of Li or K on the sheet starting from the hexagon centre the system optimises with Li or (K) adsorbed over one of the Ge atoms and not remain at the centre....
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Utilizing DFT-Computed Band Structures in Solid Physics to Investigate Superconductivity: Clues and Indicators in Band Structures
How can band structures and Fermi surfaces calculated with Density Functional Theory (DFT) be effectively employed in the study of superconductivity?
What are the key features or indications related ...
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How to calculate the charge density using Quantum Espresso?
How do I modify the input file below to calculate the charge density (DENS) using Quantum Espresso?
Input file:
...
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How to read UPF pseudopotential for ultrasoft pseudopotential simple in a fortran program
I'm currently working on calculating semiempirical local and nonlocal matrix elements for Ga. To proceed with my calculations, I need to extract specific parameters from the UPF (Unified ...
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Fermi Energy in Band Structure
I am new to this field and after going through some tutorials I was making band structure diagram of Silicon as shown in figure below, and the Fermi energy I got from SCF calculation is 6.208 eV.
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Can the electron charge density of two material systems be similar?
Broadly given two electron charge density (ECD) fields, is it possible to distinguish between the elements present in both the systems?
Since the ECD does not explicitly present any information on the ...
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Discrepancy between Force Convergence in Geometrical Optimization and SCF Calculation in VASP: Reasons and Troubleshooting Suggestions
During a geometrical optimization of ions and lattice parameters in VASP, the forces acting on atoms were minimized to less than 0.01 eV/Å. However, when performing the subsequent self-consistent ...
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Optimal choice between ISIF = 3 and ISIF = 4 for lattice parameter and atomic position relaxation in VASP calculations
In my VASP calculations, I am interested in simultaneously optimizing both the lattice parameters and atomic positions of my system.
I understand that using ISIF = 3 allows for relaxation of both ...
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How do I calculate XPS spectra for molecules to match experimental spectra?
I am trying to calculate the XPS spectra using the ICORELEVEL method in VASP, both using initial and final state approaches, for C1s and F1s electrons. My systems are single molecules.
However, my ...
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Does VASP include energy penalty contribution in OUTCAR energy of constrained moment calculation?
In VASP, one can use I_CONSTRAINED_M to constrain local magnetic moments to a certain direction in SOC calculations. However, this comes at the cost of adding an energy penalty to the total energy. ...
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What are the recent developments of TDDFT to simulate the excited properties of materials?
The time-dependent density functional theory (TDDFT) and the many-body perturbation method (GW@BSE) are considered as the two most popular and successful methods to describe the excited-stated ...
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How do I install Quantum ESPRESSO on Linux?
People, can someone please help me how to solve this problem with QE 7.0 installation:
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What do we get by integrating over the charge density data of a material system calculated with DFT?
I am confused as to whether integrating over the charge density gets us the number of valence electrons in the material system or the total number of valence electrons in the material system.
Let's ...
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My INCAR file, POSCAR, and KPOINTS are same for GGA, however after the PBE calculation, I found that the bandgap is Changing. Why is that happened?
INCAR, POSCAR, and KPOINTS are the same but for the same calculation, the bandgap is changing.
First, I relaxed the structure then did the self-consistent calculation, and bandstructure calculation. ...
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How may I calculate atomic orbital energies using VASP?
I am trying to calculate the d orbital energy of the Cu single atom, like in this page, I have tried to use the Eigenband energies minus the vacuum energy level(about 0.007eV).
...
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Modeling techniques for simulating the electronic and structural properties of Transition Metal Dichalcogenide nanotubes
Dear Matter Modeling Stack Exchange community,
I am currently working on calculating the electronic and structural properties of Transition Metal Dichalcogenide (TMD) nanotubes using DFT, with a ...
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What is the difference between non self consisent calculation and single-shot calculation?
I am new to density functional theory. My goal is to calculate magnetic anisotropy energy using the force theorem. For that, I have been told that one can run a self-consistent calculation with some ...
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Obtaining data for plotting Fermi and Coulomb holes of a hydrogen molecule
I need to visualize the exchange (Fermi) and correlation (Coulomb) hole of a hydrogen molecule to qualitatively illustrate the compensation of of both holes to form the total hole that is localized ...
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How to calculate kslice_b2 and kslice_b1 in wannierization?
How is reduced coordinates calculated in wannier90? examples 17- 18 , 29
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Are then any material property solvers (from Charge Density) available in python?
I am looking to predict properties like the Bulk Modulus, total energy, etc., all from the charge density I have as input (CHGCAR file)
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Clarifying local magnetic moment axes in VASP: cartesian vs crystal (for MAGMOM/M_CONSTR)
In VASP, one can set the local magnetic moments of each ion in a non-collinear SOC calculation along a certain direction using the MAGMOM/M_CONSTR tags. The manual linked to states that these local ...
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How to calculate anisotropic exchange J $J_{xy}, J_{xz}, J_{yz}, J_{yx}, ...$ using 4-state mapping and DFT?
In this review, the authors present several schemes to calculate various quantities like single-ion anisotropy, DMI, and anisotropic exchange J using DFT. For instance, the DMI term in the y-direction ...
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Are the cell parameters found after doing a 'vc-relax' calculation the ones used to calculate the material properties?
I created a CIF file using the experimental data from literature . After doing a 'vc-relax' calculation do I have to change the lattice parameter, CELL_PARAMETERS and ATOMIC_POSITIONS in my input file,...
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Modified Poisson-Boltzmann confusion about chemical potential and electrostatic potential
Within the Poisson-Boltzmann formalism the boundary conditions are often chosen such as $\phi^{S}$, the electrostatic potential in bulk solution far away from the interface (Galvani potential) is ...
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computing cholesky errer in nscf calculations?
after running nscf calculations I faced this problem and I don't know what could be the cause of it.
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Which researchers in electrical engineering do work related to DFT?
I would like to gain knowledge about how DFT calculations can be specifically used in the subject of electrical engineering. It would really help if people in the community can direct me towards ...
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