17 votes

When do I use the lattice parameters obtained computationally vs experimentally?

To respond directly regarding the Materials Project data, I'm a staff member there so maybe I can shed some light. Materials Project computed data is currently generated using a technique known as ...
Matt Horton's user avatar
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16 votes
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Berry's curvature and magnetic moment in TMDCs

The Berry curvature is defined as: $$ \Omega_{\mu\nu}(\mathbf{k})=\partial_{\mu}A_{\nu}(\mathbf{k})-\partial_{\nu}A_{\mu}(\mathbf{k}), \tag{1} $$ where $A_{\mu}(\mathbf{k})=\langle u_{\mathbf{k}}|i\...
ProfM's user avatar
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12 votes

Berry's curvature and magnetic moment in TMDCs

Resolution for the time reversal symmetry: I need to demonstrate: $\Omega(-\mathbf{k})=-\Omega(\mathbf{k})$ (Berry's curvature is a odd function under time reversal symmetry) Berry's curvature: $$\...
Carmen González's user avatar
10 votes
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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, ...
Anyon's user avatar
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10 votes

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

From the available information, I think it is caused by the small value of $T_{damp}$. This causes the $T$ to fluctuate wildly, which can induce unwanted bond-breaking. Best practise is to keep $T_{...
Magic_Number's user avatar
10 votes

When do I use the lattice parameters obtained computationally vs experimentally?

I will give a quick answer from my experience, but typically you want to use the computed lattice parameter. The reason for this is that otherwise you induce strain in your computed cell, but in ...
Tristan Maxson's user avatar
9 votes
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Physical origin for higher bandgaps when going from bulk to few-layers

Quantum confinement can occur when the exciton (electron-hole quasiparticle) radius is larger than the size of the semiconductor. Due to this confinement, the energy levels which can be occupied by ...
Tristan Maxson's user avatar
9 votes
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Help understanding square root notation of supercell

The main idea here is to preserve the periodic boundary conditions when creating a fractional supercell. Therefore, not all combinations are possible, such as $\sqrt{2}\times\sqrt{2}$ or$\sqrt{5}\...
Shahid Sattar's user avatar
8 votes
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When to use pseudohydrogens to passivate a slab?

TL;DR If bonds are broken in creating the lower surface of the slab, then passivation is probably a good idea. Let's start with a little bit of context: Slab calculations in computational materials ...
leopold.talirz's user avatar
8 votes

When do I use the lattice parameters obtained computationally vs experimentally?

I have to disagree with the answer of @Tristan. The x-ray diffraction, both powder and single crystal, has enough precision and quality (equipment and software) to give very good and real experimental ...
Camps's user avatar
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8 votes
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Inversion symmetry in 2D materials

Let's give it another go: In the monolayer you would place the inversion centre on the green atom. But this would reverse the direction of the trigonal prism formed by the yellow atoms. Hence, there ...
Felix's user avatar
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7 votes
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Why is VASP so popular for 2D materials?

I am not aware of any reason (and don't see) why VASP is more popular than its contemporaries for 2D materials. VASP does have some features that other packages don't, but it also has its own ...
Xivi76's user avatar
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6 votes
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VASPKIT and SeeK-path recommend different paths. Which one to choose?

If you check out this picture of the Brillouin zone of a hexagonal cell, you can see points like L, A and H are defined for a 3D Brillouin zone. This is because the k-path finding algorithms are ...
CW Tan's user avatar
  • 1,164
6 votes

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 (...
Kevin J. May's user avatar
  • 3,121
6 votes

POSCAR data file for a 2D system

You generally cannot calculate a 2D system per se with a plane-wave program, but rather you should do a vacuum slab calculation. As for graphene, you would essentially do a calculation on graphite, ...
wzkchem5's user avatar
  • 9,366
5 votes

How to derive the k-path for monoclinic lattice structure?

Not a direct answer to your question, but I hope you will still find this relevant. A very useful online tool to construct Brillouin zones and conventional $\mathbf{k}$-paths for structures of any ...
ProfM's user avatar
  • 11k
5 votes

2D Brillouin zone generator

I didn't notice this before, but the link provided in the question can already be used to visualize any 2D Brillouin zone. Since you can define the ratio of b/a, and the angle between b and a, then ...
Kevin J. May's user avatar
  • 3,121
5 votes

How can I prove that a material is ferroelectric using DFT?

As a good starting, you may take a look at this classical paper and its supplementary material: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.097601 Here I just show some general steps:...
Jack's user avatar
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5 votes
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Optical properties without LOPTICS tag

When you open the LHFCALC tag, the DFT hybrid functional type dielectric function is calculated. All the output files you obtain are calculated by ...
Jack's user avatar
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4 votes
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Modelling 2D semiconductor heterostructures including one magnetic layer with QE

Regardless of the type of material, using small smearing often helps in the convergence procedure. However, there are some caveats to look for. Always make sure that the smearing value is neither too ...
Abdul Muhaymin's user avatar
4 votes
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How to construct thin film structure of desired thickness in quantum espresso?

You can't construct the thin film itself with Quantum Espresso, but only calculate it's properties. You first have to create the unit cell of the thin film with some other software. As an example here ...
Amir K's user avatar
  • 628
4 votes

Help understanding square root notation of supercell

If you want to achieve this using VESTA you can follow what Shahid said in his answer but you have to keep in mind how lattice vectors are defined in VESTA which in turn will change the rotation ...
Khondker Shihabul Hoque's user avatar
4 votes

POSCAR data file for a 2D system

The VASP package solving the KS-equation with periodic boundary conditions (PBC). For two-dimensional materials such as graphene, you only have two periodic directions along $\vec{a}$ and $\vec{b}$ ...
Jack's user avatar
  • 14.9k
4 votes

LAMMPS calculated graphene thermal conductivity lower than expected

Your result is probably correct for this model. I'm actually not surprised that the thermal conductivity is much too low for graphene. The Airebo potential, being a classical atomistic potential, ...
WaterMolecule's user avatar
3 votes
Accepted

Quantum ESPRESSO: parameter "assume_isolated": is it applicable to slabs?

Technically I'm not answering your question of whether this method is applicable to slabs of ~3 nm thickness, but wanted to give you an answer that could be helpful anyway. I would not generally use '...
Kevin J. May's user avatar
  • 3,121
2 votes
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How to query 2D materials on materials project?

To avoid running through all the ids every time a new material is added you can use your text file where you have saved the ids already. I have written helper functions that you can use to achieve ...
Vandan Revanur's user avatar
2 votes
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How to stack graphene and hBN on top of each other?

Whenever you stack two or more materials with different cell parameter, you have to create a commensurate supercell. In most cases the supercell will not exactly commensurate with all the materials ...
Amir K's user avatar
  • 628
2 votes

Molecular dynamics method to simulate a simple fluid

Based on the comment by Magic_Number and the comment by B. Kelly, and the lack of response, and the OP not signing in for the last 7 months, I'll assume that it's enough to say that this link provided ...
2 votes

3D band structure plot

Usually people just do it by picking a path through the Brillouin zone and then plotting it in one dimension. You can use the seekpath or pymatgen (I think pymatgen has this) tools to generate paths ...
AGS's user avatar
  • 1,070

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