Questions tagged [density-functional-theory]

For questions about simulations using Density Functional Theory.

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Calculation of ionization energy for an alloy

How to calculate ionization energy for an alloy system (for eg. $\ce{Mg17Al12}$) using DFT?
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DOS projection in alternate axis for eg and t2g contributions

I am studying doping in 0D and 2D perovskites which present tilted octahedra. It is important for me to analyze the contributions in PDOS in terms of eg and t2g levels for d orbital in the transition ...
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What is the minimum basis set one should use?

If I'm interested in getting an answer that is minimally correct what is the minimum basis set level I should use? (i.e. anything less would be much less reliable) Obviously this depends on the ...
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Using "soft" constraints / bias in geometry optimization?

I study molecules weakly bound to nanoclusters and surfaces. During geometry optimization, I often run into problems like for example a small metal cluster behave nicely and has a given, stable ...
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Band structure has unusual lines in the valence band using Quantum ESPRESSO [closed]

Currently, I am working on ZnO doped with nickel and cobalt. I performed the SCF, NCF, BANDS calculation and got the results, the calculation converges without any errors. After that I used BANDS.X to ...
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Why do I get negative charge density values in the core of atoms when I perform DFT calculations with PAW?

We are all aware of the fact that negative charge densities in the atomic cores are an artefact of Density Functional theory Calculations using Projector Augmented Wave (PAW) method. But what is the ...
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A mapping between effective potential and non-interacting electrons moving on the potential

From this question and answer, I understood the Hohenberg-Kohn theorem and found that there is a one-to-one correspondence between the external potential $V_\text{ext}$ and the electron density $\rho$ ...
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HSE06+SOC calculation in VASP: How to remove false k-points?

I followed the steps mentioned in the answer of question: How to carry out HSE06+SOC band structure calculation using VASP but I found a zigzag band structure. Any idea how to remove false k-points in ...
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How to generate KPOINTS file for HSE06 band-structure calculations?

I have had a look at the example of Silicon provided here in the WIKIVASP website, and I noticed that the KPOINTS file used for ...
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Ground State energy trick for many-body electronic structure calculations?

I am an outsider to this field, so I am not sure about the validity of my work below. Let us define the following Hamiltonian from DFT:  \tag{1}H_{ij} \psi_{ij} \equiv (-\frac{\hbar^2 \nabla_i^2}{2m}...
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Crystallography: How to sample *unique* structures from configuration space? (binary alloy supercell)

I'm working with a binary alloy system (call it 'AB'), and I'd like to generate a few unique configurations for DFT purposes. My primitive cubic unit cell consists of 4 atoms; i.e. 4 positions. Thus, ...
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What correlation effects are included in KS-DFT with LDA and GGA?

This post is inspired by this post: What correlation effects are included in DFT? The Kohn-Sham density functional theory (KS-DFT) are considered to be exact and can include all correlation effects in ...
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Density functional theory and oxygen spin

I would like to perform single-point/geometry-optimization/NEB calculations on systems involving both molecular oxygens and adsorbed oxygens. Reductions by hydrogens are also involved. I am still ...
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What is the relation between enthalpy, ionization potential, internal energy and HOMO/LUMO?

Is there any relation between enthalpy, ionization potential, internal energy and HOMO/LUMO? I am dehydrogenating a molecule and I need to study the enthalpy of dehydrogenation. If I get any relation ...
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Is there a way I could calculate the pressure and use SOC at the same time?

I have been trying to find the appropriate k-point grid via convergence in quantum ESPRESSO (QE). The following is my input file. ...
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Is it possible to calculate the variation of magnetization M(T) for a diluted magnetic semiconductor?

Is there any simulation program (for example a DFT package) to determine the variation of magnetization M(T) for dilute magnetic semiconductors or doped semiconductors with different concentrations of ...
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How to extract transition density cube from .fch file in Gaussian?

I have been trying to extract the transition density cube of a simple molecule, $\ce{H_2O}$. I did a regular geometry optimization and then TD-DFT calculation with a keyword ...
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I have been looking at using Goedecker-Teter-Hutter (GTH) pseudo-potentials and I came across the abbreviation PADE. I was wondering what this abbreviation actually stood for and how it is related to ...
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Is the exchange-correlation term in Kohn-Sham equation always positive or negative?

The potential terms of the Hamiltonian in the Kohn-Sham equation are the external, Hartree, and exchange-correlation terms, which can be written as: \$V_{ext}(r) = - \sum_{i=1}^{M} \frac{Z_i} {||r - ...