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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62 views

The comparison of bandgap value of slab and bulk phase

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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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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63 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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1answer
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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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I have calculated the band structure, DOS and Fermi surface for a crystal. How do I predict physical material properties from this information?

I study the CuCo$_2$S$_4$ crystal. I did some calculations with quantum espresso, now I have band structure, density of states and Fermi surface.I'm a beginner, your help will be very helpful. If you ...
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2answers
447 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 ...
6
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1answer
50 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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66 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 ...
7
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1answer
82 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 ...
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1answer
65 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 ...
6
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1answer
51 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
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1answer
46 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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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 ...
9
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1answer
129 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 ...
10
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1answer
113 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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1answer
53 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 ...
10
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1answer
72 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 ...
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1answer
132 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 ...
6
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0answers
40 views

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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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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2answers
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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. ...
8
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1answer
95 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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1answer
161 views

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 $$ \...
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2answers
108 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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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 ...
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1answer
106 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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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 ...
7
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1answer
89 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 ...
11
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1answer
362 views

Does the spin polarised DFT calculation mean broken time reversal symmetry?

Recently, I have got to learn that if time-reversal symmetry and inversion symmetry are present simultaneously in the system we have the following conditions on energy of Bloch's states: $$E_{n,\chi }(...
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4answers
792 views

How to generate the high symmetry paths for band structure calculations?

Suppose I want to calculate the band structure of a material system along a specific high symmetry path in the Brillouin Zone. If the point group of the system is given, how can I easily compute the ...
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1answer
59 views

Quantum confinement of transition metal dichalcogenides (TMDs)

TMDs (transition metal dichalcogenides) are materials that can have a layered structure. When moving from bulk to monolayers, the bandgap changes from indirect to direct according to the image (DFT to ...
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111 views

Band Curvature looks like straight lines for (221) MoS2 Monolayer in Quantum ESPRESSO [closed]

In the band structure of (221) $\ce{MoS2}$ supercell, all the curvature are looking like straight lines. I cannot calculate band gap. ...
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Predict the density of states (DOS) diagram for rhenium oxide (ReO3) from the molecular orbital diagram [closed]

Yesterday I made this query on Chemistry Stack Exchange, and a user has felt that perhaps here I will get a quicker answer. The structure of rhenium(VI) oxide, $\ce{ReO3}$, is similar to that of ...
11
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1answer
102 views

Translating fractional coordinates resulting from conventional cell and primitive cell

I have calculated the band structure of some material where the unit cell was the conventional one (i.e. the lattice vectors are orthogonal). I'm trying now to calculate the same band structure only ...
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1answer
179 views

VASP GW+SOC band structure calculations

How may I carry out GW+SOC a band structure calculation using VASP? Could anyone familiar describe it step-by-step? I could not find any info regarding this on the VASP wiki.
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1answer
99 views

How to choose a different band path for band structure calculation using VASP?

How can I set a different band path for VASP calculation? For example I want to plot KGMK but not GMKG for graphene?
9
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1answer
152 views

What is the electrical behavior of the material with this band gap?

Presently I am doing DFT calculations to analyse the electronic structure of a material. I got the band structure as shown in the figure. I would like to know the electrical behavior of this material. ...
12
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3answers
816 views

How to create a 3D band structure from DFT band structure calculation?

How can I create such a 3D plot using matplotlib? Like the one in Figure (a) below: I want to create it using DFT bandstructure calculation result
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What are some types of topologically-relevant band degeneracies in contemporary 2D condensed matter research?

Cross-posted on Physics.SE. In the study of 2D condensed matter systems, I have seen several kinds of band degeneracies. I call 'bands' the eigenvalues to the time-independent Schrodinger equation, ...
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Band unfolding for magnetic systems [closed]

I'm trying to study the electronic structure of a 1D antiferromagnetic (in which the spin is associated with copper atoms) system, via spin-polarized calculations. The unit cell dimensions are ...
10
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1answer
234 views

How to calculate the band structure of a protein molecule

I want to calculate the band structure of a protein molecule. How can I do it using Siesta of Gaussian? I am thinking about QE/VASP as the number of atoms are 600 and computationally it is not ...
7
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0answers
70 views

Construct a parity operator at a TRIM point? [closed]

I want to calculate the band parity at some TRIM (time-reversal invariant momentum) point in Brillouin zone. Parity was defined as the eigenvalue of the inversion operator. My question is how to ...
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0answers
50 views

Is it possible to construct a tight binding matrix of high atomic layer thin film from the lower one?

Given a tight binding matrix of a thin film system with a few atomic layers, is it possible to construct a tight binding matrix of higher atomic layers thin film from the lower one? For example, I ...
12
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1answer
202 views

What does a density of states (DOS) plot show?

I have plotted the density of states using GGA-PBE exchange correlation functional for magnesium silcide but I really do not know what the equations involved are in this process, and how they relate ...
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1answer
72 views

How to solve this Bandup software problem?

I have compiled the Bandup software using this command : ./build -compiler gfortran. After that, I tried to follow the tutorial inside the directory ...
8
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1answer
134 views

How to calculate the parity of a band at a particular point in Brillouin zone

Some references mentioned that the calculation of $Z_2$ topological invariant of a crystal can be greatly simplified if the crystal contains inversion symmetry. But it involves the calculation of the ...
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2answers
492 views

How to perform band-structure unfolding in VASP?

I have created a band structure for 3x3x1 doped-supercell using VASP, and I obtained the figure below. Now I want to do band-unfolding. What are the simplest ways ...
6
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1answer
222 views

Calculating the surface state with Wannier tools

Currently I met a problem when I calculate the surface state of a topologically non-trivial thin film system. I did a DFT calculation and fit the result with wannier function. The fitting looks pretty ...
9
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1answer
181 views

What is the source of error in this mBJ-LDA calculation?

I am trying to do MBJLDA calculation for bandstructure for WS2 monolayer unit cell using VASP and following the method provided here : Band Structure mBJ-LDA using Vasp, but I am getting an error ...
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2answers
349 views

k-points value in KPOINTS file for the VASP band calculation

I'm a new VASP user, especially for the band structure calculations. I see that KPOINTS files are different for the GO/SP calculations and band calculations. For example in here it shows KPOINTS file ...