Questions tagged [topological-insulators]

For questions about modeling topological insulators (materials which are insulating in the bulk, but have conductive surface states due to specific topology of their band structure).

9 questions with no upvoted or accepted answers
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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, ...
8
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0answers
88 views

Example of a standard/archetypal/simple 4-band gapped condensed matter model with analytic results?

I am looking to study Berry phase-like phenomena in a gapped 4-band material model. In particular, I want to numerically and analytically calculate the Abelian Berry curvature integral of each band ...
7
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0answers
37 views

The quantum spin Hall phase with Z2 = 0?

I used first principle calculations to study the thin film model. An obvious crossing was shown to appear at the gamma point when the edge state was calculated, which was originally predicted to be ...
7
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57 views

Software for calculating the mirror Chern number of 2D systems?

Can anyone please explain to me how can I calculate the mirror Chern number of a 2D system? I will be very thankful if you can refer me to a package or software which can directly perform mirror Chern ...
6
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0answers
95 views

Calculating the Chern number on a 2D surface of a 3D insulator

I want to calculate the Chern number of a surface of 3D time reversal insulator. I know the 3D topological insulator was characterised by the Z2 index. And the Chern number was used characterised the ...
5
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0answers
13 views

How to plot berry curvature flux by considering plane in momentum space?

I want to plot the berry curvature flux by considering $k_x$ and $k_y$ plane in momentum space. I have experience running DFT calculations in Quantum ESPRESSO. I have tried reading the user manual of ...
5
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0answers
103 views

Why does numerical computation of Berry curvature give me a correct Berry phase when it is supposed to diverge?

I implemented the standard numerical algorithm for calculating the Berry curvature in MATLAB. For a given 2D system, I can visualize the Berry curvature over parameter space. If I sum the Berry ...
4
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0answers
36 views

What computational steps needed to characterize the Weyl points?

I am trying to learn the characterization of Weyl nodes computationally. For this, I am using Wannier90 and Z2pack codes in interface with Quantum ESPRESSO. I have done scf, nscf, bands structure, DOS,...
4
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0answers
43 views

Z2 topological index: Is this unconventional formula summed over just filled bands, or all bands?

The $\mathbb{Z}_2$ topological index is usually defined in terms of the Pfaffian of the overlap matrix, as defined by eq. 4 of Kane and Mele's paper: $$ P(k)=\text{Pf}[\langle u_i(k) | \Theta | u_j(k) ...