Questions tagged [space-groups]

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

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Is there a difference between `space_group` and `ibrav` in terms of Quantum espresso performance?

I am trying to understand the use of space_group in Quantum Espresso. I note that the keyword can be used with and without ibrav....
Wychh's user avatar
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2 votes
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How to define the space group of a new material?

I am preparing the following strcture of CdAlCRO4 using Material Studio to further study its properties. However, I am facing difficulty in deciding the space group it belongs to. How to find the ...
Habib Arshad's user avatar
4 votes
1 answer
158 views

Can a tool “Set space group” be useful?

In my program Chemcraft, a popular tool is the “Set point group” utility: it symmetrizes the molecule according to a specified point group, and then the symmetry of the molecule is correctly ...
Linkey's user avatar
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6 votes
1 answer
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About high-symmetry points in the first Brillouin zone of space group R-3m

I want to figure out the high-symmetry points in the first Brillouin zone of space group R-3m (166). For example, there are points K and M just like the bandstructure in this paper. But I can't figure ...
MathJacky's user avatar
3 votes
1 answer
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How to generate the remaining sites in a cubic lattice from a given POSCAR/cif in Python?

For example, I intend to generate the remaining sites of the Cr cubic lattice but the POSCAR file provides limited info on the number of atoms present as shown below. Is there a way to implement this ...
Pranoy Ray's user avatar
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7 votes
0 answers
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Database (or table) of functions obeying symmetry properties of space groups

I'm looking for a table or database containing mathematical functions that belong to crystallographic space groups by having the same symmetry elements. Imagine a 2D square planar lattice. It has a 4-...
Mika R.'s user avatar
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2 votes
1 answer
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How do I know which is the asymmetric unit of a unit cell?

I need the number of independent atoms in the asymmetric unit I have to introduce them in this form: ...
leire's user avatar
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2 votes
0 answers
133 views

Primitive Translation Vectors from Lattice Vectors (with varying Space Groups) [closed]

I am looking at some raw POSCAR data of some Primitive Cells, and I wonder how I can get a simplified directional representation of the lattice vectors. I have two examples: Example 1: ...
Pranoy Ray's user avatar
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4 votes
1 answer
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Reciprocal lattice and k-lattice belong to different groups in VASP

I am trying to do geometry optimization of TiO2 with VASP. Here is the POSCAR file, which I get from the Materials Project. ...
Jack's user avatar
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6 votes
1 answer
135 views

About LaCrO3 space group stability

I found two space groups of $\ce{LaCrO3}$ material Pnma and Pm-3m. If someone is familiar with this material, please help to understand which phase is more stable. what are the factors that determine ...
poonam sharma's user avatar
7 votes
2 answers
652 views

How to determine the irreducible representation of an atomic orbital at a K point?

In this paper "Unified theory of direct or indirect band-gap nature of conventional semiconductors", the authors calculated the irreducible representations of atomic orbitals at three K ...
meTchaikovsky's user avatar
8 votes
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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, ...
breadcrumbs's user avatar
16 votes
2 answers
764 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 ...
Geoff Hutchison's user avatar
5 votes
0 answers
888 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 ...
Jack's user avatar
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11 votes
1 answer
757 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 ...
Jack's user avatar
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8 votes
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93 views

How do I identify an oblique surface mesh?

I have drawn three surface meshes from a hexagonal material for the $(0001)$, $(1\bar{1}00)$ and $(1\bar{1}01)$. The first one would be the top horizontal surface of the hexagonal structure, the ...
user7077252's user avatar
12 votes
1 answer
136 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 ...
B. Brekke's user avatar
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9 votes
1 answer
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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 ...
Hitanshu Sachania's user avatar
7 votes
1 answer
428 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 ...
nougako's user avatar
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8 votes
1 answer
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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 ...
Carmen González's user avatar
8 votes
0 answers
71 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 ...
Carmen González's user avatar
19 votes
4 answers
707 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 ...
nougako's user avatar
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13 votes
4 answers
1k 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 ...
Achintha Ihalage's user avatar
11 votes
2 answers
316 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 ...
Thomas's user avatar
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18 votes
2 answers
2k 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·...
ksousa's user avatar
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22 votes
3 answers
688 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 ...
Andrew Rosen's user avatar
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23 votes
3 answers
937 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 ...
Cody Aldaz's user avatar
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