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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17
votes
1answer
429 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) ...
15
votes
2answers
230 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 ...
16
votes
2answers
548 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
133 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-...
16
votes
1answer
1k views

How to understand the 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 ...
26
votes
1answer
2k 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 ...
17
votes
1answer
244 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 ...
10
votes
3answers
251 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
15
votes
0answers
115 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^\...
11
votes
1answer
201 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 ...
11
votes
2answers
149 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 ...
12
votes
2answers
569 views

mBJ-LDA band structure calculation using VASP

I tried to create a band structure with the mBJ-LDA method using VASP. I found information that the KPOINTS file should be created according to the "0-weight (...
11
votes
2answers
115 views

Separation of valence bands in transition metal dichalcogenides (TMDs)

The image below refers to a phenomenon that occurs in TMDCs (transition metal dichalcogenides) monolayers that allowed the development of valleytronics. Why are there separate bands of different ...
11
votes
1answer
149 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 ...
11
votes
2answers
846 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 ...
10
votes
1answer
104 views

How to remove the fake k-points from vasprun.xml file in the calculation of HSE06 band structure?

Is there any script that can remove fake k-points from a vasprun.xml file for HSE06 band structure calculation? Because removing it manually is a time-consuming ...
10
votes
1answer
282 views

How to model an anti-ferromagnetic crystal in quantum ESPRESSO properly?

I'm fairly new to DFT. I would like to plot the DOS and band structure of Cobalt Oxide (CoO). But since CoO is anti ferro magnetic, how would I approach the problem? would I create an input file ...
9
votes
1answer
67 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 ...