Questions tagged [space-groups]

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

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8
votes
1answer
66 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 ...
7
votes
1answer
134 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 ...
7
votes
1answer
99 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 ...
8
votes
0answers
30 views

Symmetry of glide planes

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 ...
14
votes
4answers
261 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 ...
13
votes
4answers
280 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 ...
11
votes
2answers
284 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 ...
17
votes
2answers
159 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·...
21
votes
3answers
128 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 ...
18
votes
3answers
238 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 ...