Questions tagged [space-groups]

For questions about group theory and applications of symmetry groups of a configuration space.

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0answers
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Space group will not change in vesta

I have one unit cell of 16 atoms (4 formula unit cells) 2x2x2 unit cells. I want to construct the supercell with 32 and 64 atoms. I went in the transform and I changed the rotation matrix 4x2x2 and ...
8
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0answers
64 views

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

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, ...
19
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4answers
380 views

How is group theory used to deduce which of these integrals are equal to 0?

The number of all two-electron integrals: $$ \tag{1} \langle \phi_1 \phi_2|\phi_3\phi_4 \rangle = \int d^3\mathbf r' \int d^3\mathbf r'' \, \phi_1(\mathbf r'') \, \phi_2(\mathbf r') \frac{1}{|\mathbf ...
17
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2answers
546 views

What are good tools for visualizing glide planes and screw axes?

While there are a few tools for visualizing crystal structures, I'm particularly curious to know tools for visualizing space group symmetry, including: screw axes glide planes I teach a class on ...
5
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0answers
120 views

What's the information contained in a character table of a group? [closed]

This question has an answer on the Chemistry Stack Exchange: Understanding group theory easily and quickly. Anyone wishing to add alternative or additional perspectives that aren't already covered in ...
10
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1answer
218 views

How to analyze the band symmetry with Quantum ESPRESSO?

This question is related to this paper: J. Phys. Chem. Lett. 2017, 8, 13, 2999–3007 The above figure shows symmetry analysis for the band structure. The author writes: The band symmetry and parity ...
9
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1answer
120 views

Why does mcsqs change the space group of generated SQS?

I made a binary special quasi-random structure (SQS) using mcsqs (distributed as part of the ...
12
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1answer
113 views

What does it mean to assign group operations to distinct sets for space groups?

I am trying to understand space groups in crystallography. In International tables for crystallography, for a nonsymmorphic space group, they list some symmetry operations. 8 of them are listed under ...
22
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3answers
213 views

Enforce a space group on a given crystal structure

If I have a CIF that is P1, is there a (preferably free) code that can map the structure to some user-specified space group? I know that there are ways to do similar things with molecular systems. For ...
13
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4answers
477 views

How to analyze the space group of a relaxed structure that has fractional site occupancies

I am using VASP package to model a material that has fractional site occupancies. An appropriate supercell (cif) was generated using supercell package and converted ...
8
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0answers
47 views

Symmetry of glide planes [closed]

I am trying to understand the symmetry elements of space group number 194 (P$6_3$/mmc), which is hexagonal and has 24 symmetry operations. In the table of symmetry operations it says that it has three ...
8
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1answer
326 views

Inversion symmetry in 2D materials

Transition metal dichalcogenides (TMDs) are composed of three atomic planes and often two atomic species: a metal and two chalcogens. The honeycomb, hexagonal lattice has three fold symmetry and can ...
18
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2answers
364 views

How can I create a .CIF file from x-ray diffraction data in a paper, for compound not found in crystallographic database

I tried to recover a .CIF file (Crystallographic Information File) with the crystal structure for the compound discussed in a paper by Reuter et. al.[1], strontium hydroxide octahydrate - $\ce{Sr(OH)2·...
7
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1answer
151 views

Are there computational methods for the determination of the point group symmetry of a molecule of a given geometry?

I am aware that there exists a flowchart about how to determine the point group of a molecule with a given geometry, such as given in the diagram available in ChemLibre Texts. If we just look at the ...
20
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3answers
356 views

How to do periodic DFT calculations using Quantum ESPRESSO?

I have only done quantum mechanical computations using non-periodic wavefunctions. I'd like to try to periodic-wavefunction density functional theory. Quantum ESPRESSO seems like a good package ...
11
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2answers
296 views

Is the original structure invalid if it's found later that the material crystallises with a slightly different space group symmetry?

I am studying a material which was first discovered in the early 1960s. It was reported then that it crystallized in the hexagonal $P6_3/mmc$ space group. Recently the material was synthesized again ...