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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9
votes
2answers
225 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
234 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
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1answer
87 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 ...
9
votes
0answers
92 views

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

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 ...
14
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2answers
205 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
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1answer
71 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 ...
10
votes
0answers
79 views

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

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
63 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
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1answer
68 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 ...
11
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2answers
111 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 ...
13
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2answers
101 views

Rashba effect in 2D systems

Can someone explain how to verify the presence of Rashba effect from the band structure calculations?
9
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1answer
70 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
115 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
193 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 ...
16
votes
2answers
534 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 ...
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 ...
15
votes
1answer
363 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
144 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
124 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 ...
9
votes
1answer
231 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 ...
17
votes
2answers
2k 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 ...
26
votes
1answer
1k 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
108 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
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-...
17
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1answer
233 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
130 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
111 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^\...
16
votes
1answer
383 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) ...

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