Questions tagged [band-structure]

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

Filter by
Sorted by
Tagged with
11
votes
2answers
785 views

Is there an energy gap correction factor that needs to be used in DFT calculations?

I am a beginner and have performed the DFT calculation in Quantum ESPRESSO for calculation of the direct and indirect bandgap of Silicon. I found the indirect bandgap to be 0.6551 eV. Now, I have ...
12
votes
1answer
326 views

Si energy band values are not matching with literature values

I have performed the DFT calculation for Silicon in Quantum ESPRESO. I have tried to calculate the electronic band structure, the shape of wiggles of bands are mostly matching but the energy values ...
9
votes
1answer
51 views

What's the crystal orbital Hamiltonian population?

What's the crystal orbital Hamiltonian population (COHP) or the crystal orbital overlap population (COOP)? What's the relation between the bandstructure or density of states (DOS) and COHP/COOP? Why ...
10
votes
5answers
539 views

How to know optimal K-points grid values for good DFT calculation?

I am doing DFT calculations with pw.x executable in Quantum Espresso. For this we have to choose right K-points grid in order to perform error-less calculation. But I have no idea about how can I ...
5
votes
1answer
51 views

How to implement scissor-correction in VASP to study optical properties?

It is mentioned here that It is possible to correct for the DFT band gap error by introducing an empirical scissors correction, which is effectively a rigid shift of the conduction band with respect ...
8
votes
2answers
113 views

Supercell band structure unfolding advantages

I understand that some codes allow for or have external tools to perform band unfolding in super cell calculations. Normally these codes give band structures that are somewhat grainy and not nearly ...
9
votes
1answer
159 views

Can the fermi level of a semiconductor be below the valence band?

I was looking at the data on this page for a NiWO4 calculation. I can see unoccupied bands near the fermi level that appear to be below the band gap. What does this actually mean physically or is it ...
9
votes
1answer
168 views

How to start with structural defects in monolayer?

First of all, thank you for your help! You are so helpful every time. I would like to calculate the influence of the structural defects on the electronic structure in the HfS2 monolayer. With VESTA ...
7
votes
0answers
87 views

Calculating band structure with HSE using Open_grid (Quantum ESPRESSO)

I have executed the SCF calculation and obtained the results. After which I used kmesh.pl to extract k-points. I was able to run wannier calculations but there was an error Checking info from wannier....
11
votes
2answers
184 views

Band Structure mBJ-LDA using Vasp

I tried to create a band structure for mBJ-LDA using VASP. I found information that the KPOINTS file should be created according to the "0-weight (Fake) SC procedure" (as for HSE) I have a ...
16
votes
2answers
366 views

What are some good band-structure/DOS plotting tools/styles?

I am currently using p4vasp for drawing DOS and band-structure plots, but it is not much handy in modifying the OUTPUTS. Could you please suggest any other good software or tools for that?
8
votes
2answers
102 views

How to make a good HSE06 bandstructure for TMDC monolayer material (e.g.: WS2) in terms of VASP calculation INPUTS?

I want to perform HSE06 band-structure calculation of a WS2 monolayerwhich has the following POSCAR with ...
9
votes
1answer
126 views

How to derive the k-path for monoclinic lattice structure?

Good afternoon all, My post is inquiring about the mathematical derivation behind the Monoclinic crystal structure (c axis unique). The Brillouin zone (BZ) I really would like to derive is shown below:...
8
votes
1answer
80 views

Physical origin for higher bandgaps when going from bulk to few-layers

This is a trend that's observed in most materials that I've observed. When you go from bulk to monolayer, the bandgap of the material increases: this is true for commonly studied materials like ...
8
votes
0answers
61 views

Is the non-trivial band topology in a system, caused by spin-orbit-coupling or band inversion?

How can we know that the non-trivial band topology in a system is driven by spin-orbit coupling (SOC) or by band inversion? Based on my understanding, SOC causes the band inversion and makes the ...
13
votes
2answers
118 views

Properties that can be deduced from Band structure and DOS

Calculation of band structure and Density of States (DOS) is ubiquitous in matter modelling research publications. What are some properties that can be deduced from a band structure plot and density ...
3
votes
1answer
35 views

Interpretation of electronic band structure diagram

I want to understand the electronic band structure diagram of the following image, corresponding to $\text{MoS}_2$ (TMD): I read about DFT (density functional theory). DFT is based on solving the ...
5
votes
0answers
42 views

How can I draw the energy bands for the first and second zones of Brillouin? Is it conductor or insulator?

I want to draw the energy ($E$) diagrams for a simple cubic cell of parameter $a$, where each atom provides two electrons for the almost free electron levels for planes [100], [110] and [111]. I ...
9
votes
1answer
46 views

Absolute Valence and Conductance Band Position

Experimentally, determining the absolute valence and conductance band positions can be difficult. While DFT often underestimates band gaps, experimentally the band gap is a far more accessible ...
6
votes
1answer
59 views

Charge density wave and band inversion

Is there any connection between charge density wave and band inversion? Or is there any system in which band inversion follows the same mechanism as the CDW? I am just trying to find a connection ...
8
votes
1answer
65 views

Separation of valence bands in transition metal dichalcogenides (TMDs)

The image below refers to a phenomenon that occurs in TMDs (transition metal dichalcogenides) that allowed the development of valleytronics. Why are there separate bands of different colors in this ...
9
votes
1answer
46 views

Rashba effect in 2D systems

Can someone explain how to verify the presence of Rashba effect from the band structure calculations?
9
votes
1answer
57 views

Phonon Calculations for Bilayer 2D systems

I am facing problems in calculating the phonon band structure for bilayer 2D systems. While the band structure mostly shows positive frequencies for the 1 layer system, going to 2 layers makes some ...
13
votes
1answer
113 views

What progress has been made in modelling photocatalytic reactions on semiconductor surfaces?

For example, are there any methods to allow for modeling of photo-oxidation or photo-reduction of a compound on a semiconductor surface? It appears there has been a lot of work on the bulk properties ...
11
votes
1answer
180 views

Is there any software that can generate the electronic DOS of GaAs?

I want to calculate the density of states of GaAs conduction band (preferably each valley like Gamma, L and X). Is there any software available where I can easily generate DOS? Has the DOS of GaAs ...
15
votes
2answers
446 views

How to deduce phase transitions from a phonon calculation?

I came across the concept of using phonons to establish a material's dynamical stability, based on whether or not imaginary frequencies are present in its phonon band structure. What I am struggling ...
13
votes
1answer
724 views

How to understand time reversal symmetry in graphene

A lot of references say that the Dirac cone in graphene is protected by inversion and time reversal symmetries. How can one understand this statement? How can one show explicitly that the gapless ...
15
votes
1answer
254 views

Why is the band gap of graphene “opened” in this VASP calculation?

I used VASP to do the band structure calculation on Graphene. Originally I would expect that the Dirac cone can be observed in the K point. If we watched qualitatively, we can see this behavior. But ...
14
votes
1answer
121 views

conceptual problem about the energy band along the High symmetry point in the Brillouin zone

When we calculate the band structure of certain material, we only have to calculate the value along the high symmetry point which enclose the Irreducible Brillouin Zone. Why the information lie in the ...
12
votes
1answer
83 views

DFT vs tight-binding solutions for a Dirac cone in graphene: Why is the DFT version squeezed?

I'm a beginner at DFT calculations with VASP software. I use it to calculate the band structure of graphene and I obtain the following result: I used it to calculate the band structure of graphene ...
8
votes
1answer
69 views

What is the meaning of fat bands?

I came across the band structure colored as bellow1: As you can see, each band was colored depending of the atom contribution to each band. Googling, I found it was done using the concept of fat ...
14
votes
1answer
588 views

Calculating HSE06 band structures on Quantum ESPRESSO

I am currently trying to figure out how to compute band structures for my system, using the hybrid functional HSE06. I'm doing this on Quantum Espresso. As I understand, there are a handful of ways to ...
22
votes
1answer
335 views

What is band inversion and how to recognize it in band structure?

Band inversion is a key ingredient of a topologically nontrivial material$^1$. What is band inversion? How to recognize it in a band structure? What conclusions can I infer if I observe band inversion ...
14
votes
1answer
89 views

Tools for Valleytronic Research

Similar to spintronics, which attempts to use electron spin polarization as the bits (or possibly qubits) in a logic device, valleytronics attempts to use a combination of the spin and "valleys&...
13
votes
1answer
117 views

Semi-empirical software for bands calculations

In Semiconductor Physics, one of the main parameters of interest is the band gap. It is known that, in DFT, there are functionals that underestimate it. I came across the MOPAC program, a semi-...
17
votes
1answer
193 views

How does the mBJ potential give an accurate band gap as compared to LDA and GGA?

I am not able to understand the literature on how the modified Becke-Johnson(MBJ)$^{[1]}$ potential gives an accurate bandgap. Can someone please help? Thank you. The formula for the potential can be ...
16
votes
1answer
91 views

How to ensure a smooth band structure?

I performed an HSE06 calculations using VASP and the calculated band gap is in good agreement with experiment. However the band is not smooth, with very sharp, zig-zag like features. How to improve ...
15
votes
0answers
65 views

How to find the projected Hamiltonian for lowest flat-band in general?

In [1], starting with the bosonic Hamiltonian (Eqn. 1) for the dice lattice model with half flux density (with Ahronov-Bohm phases incorporated), \begin{equation} H=-t\sum_{\langle j,\mu\rangle}(a^\...
15
votes
1answer
189 views

Are there differences in accuracy and reliability between the frozen phonon method and Density Functional Perturbation Theory?

When proposing or predicting new materials, whether in the bulk or in two dimensions, it is important to discuss the stability of the system. This is usually done through thermodynamics and(or) ...