# Tag Info

Accepted

### How to understand the time-reversal symmetry in graphene?

Two-band model for graphene. To simplify the discussion of Dirac points, it is sufficient to consider a nearest-neighbor tight-binding 2-band model for graphene. This is a spinless model because spin-...
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### How to explain to a five year old why "DFT with local exchange–correlation functionals do(es) not describe van der Waals interactions accurately"?

Standard DFT functionals are based exclusively on local information, e.g. for a GGA functional $$E_{xc} = \int n({\bf r}) \epsilon_{xc}(n({\bf r}), \nabla n({\bf r})) {\rm d}^3r$$ while van der ...
• 14.6k
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### Why is the band gap of graphene "opened" in this VASP calculation?

The reason why graphene has Dirac points at K and $-$K is because of a combination of time reversal and inversion symmetries. Therefore, if you impose these symmetries in your VASP calculation, there ...
• 10.4k

### How to explain to a five year old why "DFT with local exchange–correlation functionals do(es) not describe van der Waals interactions accurately"?

I'll turn my comment as an answer, as requested by the OP and Nike. Susi Lehtola's answer has already pointed out that dispersion (which may be a more accurate term than van der Waals interaction here)...
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### What's the past and future of 2D materials since graphene?

Actually, if you allow for quasi-2D systems, graphene has had a recent renaissance starting with the experimental discovery of correlated states in "magic angle" twisted bilayer graphene, ...
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### How to separate the band structure of different materials in heterostructures using Quantum ESPRESSO?

I believe what you are referring to is a "projected" or "fat" band structure diagram. By assigning colors (or line thickness) to a basis on which you project the Kohn-Sham states (...
• 2,891
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### Binding energy calculation for Zn atom on armchair graphene slab?

As mentioned by @Camps in the comments, the Zn reference used in the paper is almost certainly that of an isolated Zn atom in the gas phase. If I understand correctly from briefly scanning the paper, ...
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### Does the Mermin-Wagner theorem influence the stability of graphene?

This Physics Stack Exchange thread answers this question very well. Apparently, the length scale of such "logarithmic divergence" is actually merely in the order of atomic distances even if ...
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### Help with understanding topologically-protected edge states in domain wall systems

I think my understanding on this problem has improved somewhat. Let me try to clarify my confusions. If anyone sees issues with this reasoning, please let me know. The idea of phases in this context ...

### Wavefunction magnitudes being degenerate everywhere on parameter space even though energy degeneracies occur at isolated points?

This is a somewhat handwaving answer but I think it gets the main point across: We should start by pointing out that the two components of your eigenstates represent the wave function amplitudes on ...
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