Questions tagged [supercell]

Questions about or related to supercells.

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12 votes
2 answers
334 views

How to sort a supercell for a molecular crystal?

I am trying to build a supercell of the following (below) molecular crystal from its .cif file. How do I sort a supercell here according to each molecule in the supercell? I'm not tethered to a ...
  • 1,373
9 votes
2 answers
649 views

Help understanding square root notation of supercell

I often see supercells and slabs explained like this: $2\sqrt{2} \times 6$ slab of $\ce{MoS2}$ (001) $\sqrt{2} \times \sqrt{2} \times 2$ supercell of $\ce{Y Ba(1−x)Sr(x)CuFeO5}$ (see here). Take $\...
9 votes
1 answer
112 views

Different band structure in supercell, but not due to band folding

This is my first time asking a question - if I mess something up please let me know and I'll amend. I believe this goes beyond questions on how to use QE so here seems appropriate over the QE forums. ...
  • 131
9 votes
0 answers
154 views

Difference of high-frequency and static dielectric constants? [closed]

I found in an article [1] the following definition of FNV (Freysoldt, Neugebauer and Van de Walle) energy correction term for a charged defect in a cubic supercell: $$E_{\text{corr}}=\frac{\alpha_Mq^2}...
8 votes
2 answers
369 views

Extracting the coordinates of a super cell in Vesta or Avogadro

I am trying to use a program such as Vesta or Avogadro to build a super cell from a .cif file for a molecular crystal. In neither program can I seem to figure out how to order the output of the ...
  • 1,373
8 votes
1 answer
200 views

Using LAMMPS for a small system

I want to run a classical molecular dynamics simulation on silicane using LAMMPS. Since I don't have access to any HPC nor do I have a powerful desktop PC, I'm planning on making the system small. By ...
  • 1,091
8 votes
0 answers
77 views

Crystallography: How to sample *unique* structures from configuration space? (binary alloy supercell) [closed]

I'm working with a binary alloy system (call it 'AB'), and I'd like to generate a few unique configurations for DFT purposes. My primitive cubic unit cell consists of 4 atoms; i.e. 4 positions. Thus, ...
7 votes
2 answers
274 views

What is the meaning of the "PRIMCELL.vasp" file generated by VASPKIT tool during bandstructure inputs generation?

When I use VASPKIT tool to generate K-path KPOINTS file for Bandstructure calcualtion of a 4x4x1 supercell of a pure material, ...
  • 5,531
7 votes
1 answer
191 views

How could I fold a specific high symmetry point to the Gamma point?

How could I get the Brillouin Zone of 2*2 supercell? I tried to use see k-path website, but when I upload a supercell, it still generates the Brillouin Zone of the unit cell. What I want to do is to ...
  • 1,793
7 votes
1 answer
112 views

Different band gap observed in unitcell and in the supercell

I calculated the bandgap for one system in the unit cell and in the supercell of 2x2x1 and 3x1x1. Although 3x1x1 gives the same bandgap as I got from the unit cell (1.79 eV) but 2x2x1 is giving 1.75 ...
6 votes
1 answer
100 views

How to construct thin film structure of desired thickness in quantum espresso?

I want to study the properties of thin films using DFT calculation. I have done the bulk crystal calculations in Quantum ESPRESSO but have no idea how can I construct the thin film of desired ...
  • 2,421
5 votes
1 answer
340 views

ASE: why do I get warnings about "monoclinic" and "orthorhombic" not being interpreted?

I am trying to use ASE (Atomic Simulation Environment) to build a supercell of some molecular crystals and then output the result to a file with the atoms given in a specified order for each molecule, ...
  • 1,373
5 votes
1 answer
87 views

Number of k-points vs number of electrons: which is more significant in terms of computational cost for plane-wave calculations?

When using plane-wave codes for solid-state calculations, which computational parameter is more significant in increasing the computational cost: number of electrons or number of k-points? I ask this ...
  • 171
5 votes
1 answer
161 views

Supercell model for a disordered system in phonon calculations using the harmonic approximation

I studied a disordered state (FCC solid solution) and used a special quasirandom structure supercell with 32 atoms to represent the system. After relaxing it thoroughly with ...
4 votes
2 answers
128 views

Energy per unit cell in NWChem differs for different supercells despite the same k-points density

I try to compute the unit cell energy of the $\ce{Ti2CO2}$ MXene with NWchem. Computing the 1x1 supercell with 4x4x1 K-points grid I got -1875 Ha. Computing the 2x2 supercell with 2x2x1 K-points grid ...
  • 430
3 votes
2 answers
56 views

What happens to the position coordinates of the nearest neighbors in supercell studies?

Can anyone tell what happens to the position coordinates of the nearest neighbors when we choose to study supercell of the same material. That remains intact or any changes will be there? For example ...
3 votes
1 answer
71 views

How to make left and right handed material interface using python

I have a crystal structure, a B20 compound. I want to make an interface of that bulk compound with left and right-hand material. Is there any python code for writing such interfaces. or for writing ...
  • 47
2 votes
0 answers
40 views

Confusion in primitive, conventional and supercell crystal structure

I am doing the DFT calculations in Quantum ESPRESSO code. I have 2 different pwscf input file of the same crystal. I am confused which one is representing primitive, conventional and supercell ...
  • 2,421