Questions tagged [band-structure]

Questions about the band structure of solids. Band theory forms the foundation of the understanding of all solid-state devices.

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Optical Band gap determination from absorption coeffecient using DFT

I am currently working with a perovskite material which shows forbidden transitions. Older studies used bigger values of $\alpha$ in HSE06 calcualtions(to match with experimental Band Gap) but a ...
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2 votes
0 answers
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Why band inversion leads to twisted wavefunction?

ProfM answered that wavefunction is twisted in topological material while is not in normal insulator (What is band inversion and how to recognize it in band structure?) I can kind of understand this ...
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3 votes
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How to carry out Spin-projected band structure calculation( as shown in figure)using VASP?

How to carry out Spin-projected band structure calculation( as shown in figure)using VASP? I couldn't find any good source for this kind of plotting, is there a code for this kind of plotting other ...
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11 votes
1 answer
335 views

Software recommendations to construct band structures using tight binding

I am at the beginning of computational materials modeling. My objective is to calculate the electrical conductivity of a system that consists of several thousand atoms, and running DFT calculations is ...
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10 votes
1 answer
271 views

Should one perform geometry optimisation before calculating electronic/phonon band structures via DFT?

I am new to DFT calculations and I would like to get the electronic and phonon band structures of FeSn (1 kagome layer and 1 Sn layer in between). My question is, is it absolutely necessary to first ...
5 votes
0 answers
63 views

Standard Practice for Relaxation, Band Structure and Density of States Calculations wrt smearing method

My question is mainly one about consistency in the smearing method used for a standard "geometry relaxation + band structure (BS) + density of states (DOS)" set of calculations. This is a ...
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1 vote
0 answers
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How Can I Create a 2D Silicon Carbide Structure using VESTA

I'm just getting started with VESTA. SO I'm fairly new to it. Can anyone suggest me how to build a 2D structure of Silicon Carbide (SiC)? Or any documentation would also help. Thanks .
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3 votes
0 answers
51 views

Zig zag straight lines bands from Quantum Espresso calculations

During band structure calculations in Quantum espresso I found that the bands are coming in Linear form and not curvature. Why is this happening? Is there any explanation for this? Which parameters ...
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2 votes
1 answer
62 views

How to increase high symmetry points in band structure?

Can I repeat high symmetry points manually by copying the sequence on input file?
5 votes
1 answer
153 views

How to find which atoms/bonds contribute to the particular section of band structure?

In this paper, in the first sentence of page no.6723, the authors attribute a particular section of band structure (in momentum space) to the bonds/ atoms in real space. I would like to know methods ...
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4 votes
1 answer
75 views

3D band structure plot

I am trying to plot 3D band structure of my system of interest. I have used Quantum Espresso software for calculating the band structure and plotted 2D band diagram. But from here I am unable to ...
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5 votes
0 answers
43 views

About the mechanism of opening of the band gap in topological insulator with the inclusion of SOC

When we work on the topological insulator (protected by time reversal symmetry ), it is often said that the SOC is the main ingredient because it is a way to open a gap when the band inversion present....
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4 votes
0 answers
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Extracting hopping parameters for band structure calculations from Atomic coordinates

I have relaxed atomic coordinates of bilayer graphene obtained from LAMMPS MD simulations. I want to extract hopping parameters (tight binding model or continuum model) to obtain the band structure of ...
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6 votes
1 answer
228 views

How to transform the k coordinate into the k path used in the band structure?

When drawing the band structure, I need to transform the coordinate of k-points into a k-path, but I am not sure what the formula is. I checked the result of siesta,...
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11 votes
2 answers
245 views

Temperature Effect on Band gap in solid state calculation

I am new in solid-state calculation field. There has been pretty well-known to use DFT or DFT+U method to calculate the electronic properties such as the band gap for metal, and semiconductors. When I ...
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5 votes
1 answer
88 views

Cross-post: Matrix elements <n,k|x|n',k'> for Bloch states

Cross posted at Physics.SE I believe this is just elementary QM, but I'm getting awfully confused. The question is drawn from this paper on Wannier-Stark localization (but is self-contained). Let: \...
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3 votes
1 answer
105 views

What does it mean if the Fermi level crosses into the valence band? How about into the conduction band?

Just recently got into DFT and I've been doing a few calculations on my own on Quantum Espresso. I've come up with electronic band structures for materials that I've been looking at and I was hoping ...
4 votes
1 answer
240 views

Why I have difference between DOS and BAND gap?

As they advise everywhere, SKF should be considered without SOC, and already in NSCF, spin-orbit interaction should be included. But what is the actual question, as I know, band splitting occurs with ...
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1 vote
1 answer
319 views

Repeated error in Quantum Espresso "Error in routine potinit (1)"

I have been trying to perform some calculations in Quantum espresso on mono-layer Borophene. Initially, I have optimized the structure which succeeds. Subsequently, I am trying to use this optimized ...
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9 votes
1 answer
148 views

Different band structure in supercell, but not due to band folding

This is my first time asking a question - if I mess something up please let me know and I'll amend. I believe this goes beyond questions on how to use QE so here seems appropriate over the QE forums. ...
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16 votes
1 answer
174 views

Easy ways to generate "teaching" band structures in Python?

I'd like to introduce band structure to a class of undergraduate chemists, along the lines of Roald Hoffmann's Solids and Surfaces. That is, I'd like to start with a s-band in 1D, which is easy ...
9 votes
2 answers
435 views

How is the right k-path chosen for band structure?

When generating the kpoint by vaspkit for two compounds that have the same lattice system, I found the kpath is G–X–S–Y–G–Z–U–R–T–Z|Y–T|U–X|S–R. But why in the article (as shown in the picture) was a ...
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8 votes
2 answers
301 views

Why do we need to use fake k-points when doing HSE band structure in VASP?

I want to know why we need fake k-points in HSE band structure calculation? I mean why we can't take a simple high symmetric path like we do in PBE calculation?
4 votes
0 answers
117 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 ...
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2 votes
0 answers
39 views

How would surface state affect the band gap value of semiconductors?

I am struggling to figure out the relationship between bandgap value and surface states. To my understanding, when considering the material that includes surface, there would be some surface states in ...
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6 votes
1 answer
153 views

What parameters should be checked on both unit cell and super cell to make sure the calculations are going fine?

Question is based on further learning about the previously asked question - Do NSCF calculations on Supercell gives different band gap than the Unit Cell? How should I compare SCF and NSCF ...
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8 votes
1 answer
156 views

Do NSCF calculations on Supercell gives different band gap than the Unit Cell?

NSCF (non-self-consistent field) calculations are done on a dense mesh. I did it on a unit cell. Then since I have to try using a supercell for alloying, I am doing calculations to see the results of ...
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11 votes
2 answers
633 views

Why the band structure of a slab is not smooth?

I am trying to calculate the band structure of a TiO2-Rutile slab, but the result I got is not very smooth, and the result shows it is an indirect gap material, but the bulk phase of TiO2-Rutile is a ...
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6 votes
1 answer
166 views

Is it necessary to do self-consistent calculation after structure optimization?

When calculating the band structure of a material, I have been told that at first, I need to do structure optimization to get a stationary structure(1st step), and then keep the atoms' position fixed, ...
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6 votes
0 answers
261 views

How to interpret density of states and band structure of a material? [closed]

I am new on the VASP platform, and have learned how to calculate any material's DOS and Band structure. However, I don't know how to interpret these properties. Can you recommend resources that ...
8 votes
1 answer
121 views

Which software is suitable for visualizing the electron wavefunctions in a crystal?

I'd like to use the tight-binding model with a linear combination of atomic orbitals. It should show the full energy bands, as well as the spatial probability distribution for each eigenfunction of ...
9 votes
1 answer
127 views

How to identify localized surface states in the band structure

After calculating the band diagram of a structure, is there a way to identify localized surface states? I am working with Si nanowires with different cross sections. I want to determine the band gap ...
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6 votes
1 answer
268 views

SC vs NSC Fermi energy in VASP, which is correct?

While calculating the band structure using VASP, we usually take two steps: one is the self-consistent run to get the right CHGCAR file; and the other is a nonself-consistent calculation to generate ...
5 votes
1 answer
79 views

Tool to saturate the dangling bonds at the surface of nanostructures

When it comes to studying 2D, 1D or 0D nanomaterials, saturating the dangling bonds in the surface helps remove unwanted localized surface states from the band structure 1. However, so far I have not ...
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8 votes
1 answer
144 views

How to change the magnetization direction in Quantum ESPRESSO?

I have a magnetic crystal system. I want to calculate the total energy of the system if the magnetization direction is aligned in different directions such as [110], [010]. By default Quantum ESPRESSO ...
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9 votes
1 answer
190 views

Geometry optimization using DFT

I have been attempting to optimize the structure of a Si nanowire using SIESTA. The original structure fed into the optimization is as follows. Once it is optimized, the structure would change to ...
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10 votes
1 answer
257 views

Error in nscf calculation while considering Spin Orbit Coupling in Quantum ESPRESSO

I am trying to do the band structure calculation considering the Spin Orbit Coupling but getting the following error: ...
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8 votes
1 answer
68 views

Effective mass convergence

What's the point of using extremely denser k-grid for extracting curvature effective masses? I saw in some publications that they use extremely dense k-grid for band structure calculations for ...
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10 votes
1 answer
93 views

What is signified by the properties of the electronic band structure?

When considering the band structure of two materials or two structures along a specific k path, what exactly is meant by the gradient and the distance between band lines? Does this show any ...
3 votes
2 answers
505 views

Band Structure Calculation with HSE06 Hybrid Functional in VASP

I am using HSE06 hybrid functional to calculate the band structure. I copied IBZKPT file as the KPOINTS file and pasted the k point path for the band structure after this file. The k point path for ...
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6 votes
0 answers
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Constructing the symmetry operator from k.p Hamiltonian [closed]

I have a question regarding to how to construct an operator from k.p Hamiltonian. Maybe there are some problems in my understanding, I hope you can point me out and correct my description if I made ...
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6 votes
1 answer
142 views

Nanowire Band Structure using Siesta DFT

I'm working with the Siesta DFT software, and managed to reproduce the band structure of bulk Si without any issues. However, when trying the same with a Si nanowire, the band structure looks nowhere ...
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9 votes
2 answers
75 views

Can these Band-gap specifications be attributed to a Half-Semiconductor material?

A Half-Semiconductor is a material with a narrow band-gap for one spin channel and a wide band-gap for the other channel. ...
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7 votes
1 answer
246 views

If Gaussian and Tetrahedron smearing method lead to different Fermi energies, which one is the correct?

In addition to this post, The used settings were : DOS: ISMEAR = -5 SIGMA = 0.2 (default value) BS: ISMEAR = 0 SIGMA = 0.1 Now,...
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11 votes
1 answer
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Transition dipole matrix element

When doing DFT calculations of periodic solids, from either $\mathbf{k \cdot p}$ perturbation theory or simply using the trick $\mathbf{r} \rightarrow i\partial_{\mathbf{k}}$, one can obtain $$ \...
4 votes
2 answers
285 views

What is the source of this band structure and DOS inconsistency?

Using VASP, I have conducted DOS and BS calculations of a Ti-doped $\ce{MoI3}$ monolayer using the following: POSCAR: ...
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5 votes
0 answers
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HSE06+SOC calculation in VASP: How to remove false k-points? [closed]

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 ...
10 votes
1 answer
238 views

What is the difference between a half metal (HM) and a spin gapless semiconductor (SGS)?

I would like to know what is the difference between a Half metal (HM) and a Spin Gapless Semiconductor (SGS) in terms of definition and DOS/Bandstructure appearance.
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5 votes
2 answers
89 views

Interpretation of effmass module

Currently, I am trying to figure out the effmass module. I'm newly into effective mass stuff and I'm able to run it and generate effective masses. However, I'm facing some trouble understanding it. Is ...
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7 votes
1 answer
255 views

Calculating the band structure of Bi2Se3 with spin-orbit coupling

I would like to simulate $\ce{Bi_2Se_3}$ using a DFT calculation on VASP. However, it seems I am not able to get a result; the electronic steps take $\sim \infty$ of time to complete. Here are the ...
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