Questions tagged [graphene]

The properties of graphene and their modelling.

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6
votes
1answer
56 views

Help with understanding topologically-protected edge states in domain wall systems

Let's say that I have a simple domain wall system for the following Hamiltonian with added on-site potential $M(x)$: $$\tag{1} H(k,M)=-t \sum_{\delta} [\cos(k\cdot\delta)\sigma_x-\sin(k\cdot\delta)\...
10
votes
0answers
74 views

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

Cross-posted here. Consider the usual simple 2-level gapless graphene Hamiltonian in momentum-space where the energy dispersion is degenerate/gapless at a Dirac point: \begin{equation}\tag{1} {\small ...
6
votes
1answer
74 views

Help with definitions in k-space twisted bilayer graphene model

I am trying to numerically do calculations using Eq. 8 of MacDonald's simple model for twisted Bilayer graphene. I only want to calculate the Berry phase. However, I don't think I have my definitions ...
4
votes
0answers
39 views

How to design Graphene metasurface using COMSOL? [closed]

I want to simulate a graphene based metasurface using COMSOL. Can anyone tell me the steps of defining Graphene in COMSOL or provide any tutorial for the same?
16
votes
1answer
2k 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 ...
11
votes
1answer
107 views

Binding energy calculation for Zn atom on armchair graphene slab?

I am trying to repeat the result of this paper for Zn absorbed on the armchair graphene slab. The relaxed top and side structures are the following: The relaxed structure is almost the same as the ...
10
votes
1answer
300 views

What's the past and future of 2D materials since graphene?

Since the discovery of graphene in 2004, two-dimensional (2D) materials have been a hot topic in the community of condensed matter physics, which can be considered as the candidate for next-generation ...
-4
votes
1answer
112 views

Has there been research on improving the strength of graphene-based materials?

I read that brittle materials tend to have an observed strength much less than its theoretical strength because they tend to have surface cracks and whatever tension is applied gets greatly magnified ...
12
votes
0answers
165 views

Sample LAMMPS file for graphene growth on a metal surface [closed]

I am working with graphene growth on metal substrates. But I need some sample files to know if I am doing it in the right way because running multiple simulations in LAMMPS takes a lot of time. Can ...
5
votes
1answer
169 views

How to separate the band structure of different materials in heterostructures using Quantum ESPRESSO?

So, I know that to calculate surface band structure of a material, you have to take its 2D system eg. single or few-layered. But, how to find the surface band structure in the case of heterostructures....
11
votes
1answer
308 views

What does capital sigma followed by an integer (Σn) mean in the context of grain boundaries?

I've just run across a nomenclature for coincidence lattices at grain boundaries which uses a capital greek letter sigma followed by an integer. For example Grain Boundary Engineering & ...
9
votes
1answer
60 views

Does the Mermin-Wagner theorem influence the stability of graphene?

Prior to the discovery of graphene, the Mermin-Wagner theorem was used to argue that purely two-dimensional materials would not be stable as two-dimensional order would show logarithmic divergences at ...
12
votes
1answer
204 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 ...
20
votes
1answer
133 views

Why can't I reproduce the behavior of an H-saturated graphene flake?

I'm trying to simulate a graphene flake with its edge C atoms saturated by H atoms, in a temperature ramp from 300 K to 1600 K, using LAMMPS and the AIREBO potential proposed by Stuart et al. in 2000. ...
15
votes
1answer
511 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 ...