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11 votes
Accepted

Fermi Energy in Band Structure

In electronic structure calculations of finite systems, there is a well-defined energy scale: 0 is the vacuum energy, and any electron with positive energy is unbound. For materials, the story is ...
elutionary's user avatar
  • 1,006
8 votes

Reference energy for bands

The "zero" of energy is arbitrary, it doesn't affect any properties (total energy is not an observable). In particular, in a plane-wave DFT simulation you will almost always be using a ...
Phil Hasnip's user avatar
  • 8,052
6 votes

How do I obtain CB and VB values from Quantum ESPRESSO?

I would recommend to obtain VB top and CB bottom energy values from the output file. The occupation numbers are listed if 'verbose' mode is active. In any output mode the energies should be printed ...
Leon A's user avatar
  • 101
6 votes

How to choose the best U value for studying the electronic properties?

U values are in general non-transferable the U-value found in the literature will not give you the same band gap in general unless you know the exact structure, pseudopotentials, DFT code and their ...
Abdul Muhaymin -Free Palestine's user avatar
5 votes
Accepted

Significant external pressure in non-SCF calculation results

The energy, pressure, forces etc are only accurate for a converged K-point grid. When you do a band structure calculation, you are sampling a tiny subset of reciprocal space and e.g. pressure will ...
Tyler Sterling's user avatar
5 votes

Indirect to direct band gap transition in SUPERCELLS?

This is allowed, in fact you can almost always construct a supercell where this has to happen. Consider the band eigenvalue at k-point $\vec{k}=(0,0,\frac{1}{p})$ in a given unit cell; if I now make a ...
Phil Hasnip's user avatar
  • 8,052
5 votes

Why do we specifically need an SCF-generated charge density for calculating the density of states (DOS) and band structure?

Background At the heart of a conventional DFT simulation are the Kohn-Sham equations, $$ \left(-\frac{\hbar^2}{2m}\nabla^2 + \hat{V}\left[\rho\right]\right)\psi_{bk} = E_{bk}\psi_{bk} \tag{1} $$ where ...
Phil Hasnip's user avatar
  • 8,052
5 votes

How do I obtain CB and VB values from Quantum ESPRESSO?

From the graph you presented: Select the Brillouin $\Gamma$ point, $G$ in the graph (this is for a direct gap system). Look for where the Fermi level is. In the graph, it is indicated by the red ...
Camps's user avatar
  • 23.6k
5 votes

About high-symmetry points in the first Brillouin zone of space group R-3m

As described on the paper, the system presents a hexagonal unit cell. From the paper recommended by @MathJacky (if you don't have access to the published paper, there is an arXiv version), we have ...
Camps's user avatar
  • 23.6k
5 votes

Symmetries and band structure

The answer to that might be very long and you want to avoid math in here so I will try my best to explain how I understand it but with a little math at the end. Let’s start from the general connection ...
Jaafar Mehrez's user avatar
4 votes
Accepted

Determining the Nature of a Material's Band Structure: Metallic or Semi-Metallic?

(Edited after discussion with the asker and seeing the zoomed-in band structures. A commenter suggested adding Addison of hybrid functionals as a correction to the band gap underestimation of [...
elutionary's user avatar
  • 1,006
4 votes

How to create an input file for band calculation

A general idea is: Determine the crystal symmetry of your system. Select the path between high symmetry points to calculate the bands (follow one of these links: 1, 2, 3 or read this paper). Use a ...
Camps's user avatar
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3 votes
Accepted

Can a material be a conductor in one direction and a semiconductor in another direction?

If I understand your question, the answer is yes. Really, the only requirement is anisotropy. Consider e.g. a half-filled 1d chain. It is metallic along the chain and insulating perpendicular to it. I ...
Tyler Sterling's user avatar
3 votes

Exploring Band Structure and Density of States Visualization Tools for VASP Calculations

sumo It has been suggested before here on MMSE. For VASP calculation, sumo can be used to easily plot both the density of states and the band structure. Here is the main website and here is the ...
Abdul Muhaymin -Free Palestine's user avatar
3 votes

Quantum ESPRESSO: how to calculate mobility?

A simple equation for the electron mobility is $\mu=e\tau/m^*$. Here, $e$ is the electron charge, and the effective mass $m^*$ can be obtained by fitting a parabola to a band minimum/maximum as ...
leopold.talirz's user avatar
3 votes

Effect of carrier concentration on electrical conductivity

In case someone else starts wondering on the same phenomenon, what I figured out is as follows. When observing the band structure of the material, it should be noted that only electronic states with ...
PBH's user avatar
  • 2,653
3 votes

How do I obtain CB and VB values from Quantum ESPRESSO?

To obtain both the VB and CB you will have to run scf calculation by using the nbnd command (the number of Kohn-Sham states) with a value basically the same as the ...
Youssef Chlikhy's user avatar
3 votes

How to create an input file for band calculation

Using Quantum ESPRESSO, you can follow one of several routes to calculate the band structure of your material. The number of input files depends on the specific path that you follow. All routes have ...
Abdul Muhaymin -Free Palestine's user avatar
2 votes

How to create an input file to run band structure calculation in Quantum ESPRESSO?

The path I follow in this answer is to first getting the ground state using an SCF calculation, then performing an NSCF (calculation='bands') run using appropriate ...
Abdul Muhaymin -Free Palestine's user avatar
2 votes

Variation of Conduction band minimum and valence band maximum with applied strain in semconductors

Generally speaking, one would expect that the band edges should vary linearly with applied strain, especially for small strains. This linear relationship is often observed in many materials and ...
Jaafar Mehrez's user avatar
2 votes

How to add the scissor operator in Quantum ESPRESSO input?

This comment by Abdul Muhaymin provides the following thread from the Quantum ESPRESSO mailing list which I'm including below (for me, I couldn't even visit the thread online because my browser told ...
2 votes

Exploring Electronic Properties: Density of States (DOS) and Band Structure Analysis with Gnuplot?

I would recommend watching QuantumNerd's videos, where he explains how to calculate and plot using gnuplot the following: DOS in Quantum Espresso Band structure in Quantum Espresso . He plots this ...
Vladislav Gladkikh's user avatar
1 vote
Accepted

VASP & Q.E - Crossing in the band structure in Weyl (nodes) and Dirac materials

The problem was really the number of points per line in KPATH.
Gabriel Elyas's user avatar
1 vote

Exploring Band Structure and Density of States Visualization Tools for VASP Calculations

You could use gnuplot. There is a lot of documentation online and is covered in this answer: mattermodeling.stackexchange.com/q/4753/8414
Rubi Agrawal's user avatar
1 vote

How to add a break into CASTEP k-point path

I have an updated version of the dispersion.pl script which detects and correctly handles breaks in the path. This may be downloaded from https://github.com/krefson/...
Keith Refson's user avatar
1 vote
Accepted

How to change color of bands in PyProcar?

Changing band color in plain mode Can be achieved by setting the color argument in the bandsplot function ...
Vandan Revanur's user avatar
1 vote

Problem with k-points with pw2wannier

I assume that you used open_grid.x in order to expand the k-point grid from IBZ to full BZ. In this case the k-point mesh should be taken from the output of open_grid.x. Also I found that when using ...
Leon A's user avatar
  • 101

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