Primitive cell parameter given chemical unit cell info

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Discussion Overview

The discussion revolves around the challenge of constructing primitive cell information from chemical unit cell data, particularly in the context of using ab initio computational packages. Participants explore tools and methods for generating primitive cell parameters and symmetry equivalent positions based on provided crystallographic information.

Discussion Character

  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant inquires about the process of constructing primitive cell information from chemical unit cell data, noting that ab initio packages require this specific format.
  • Another participant suggests using the Materials Project and the NIST Inorganic Crystal Structure Database as potential resources for obtaining relevant information.
  • A later reply clarifies that generating all symmetry equivalent positions from a single Wyckoff position is a key aspect of the inquiry, referencing the International Tables for Crystallography and the Bilbao Crystallographic Server as sources for this information.
  • There is a caution mentioned regarding the existence of two possible choices for the origin in some cases, which may affect the construction of the primitive cell.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a single method or approach, and multiple perspectives and resources are presented without resolving the overall inquiry.

Contextual Notes

Limitations include the dependence on specific definitions of primitive and unit cells, as well as the potential ambiguity introduced by different choices of origin in crystallographic data.

bsmile
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Experimentalists usually provide chemical unit cell information including full symmetry (space group) information of the crystal together with coordinates of independent atoms. But this cannot be directly used by ab initio packages, which requires either primitive cell or unit cell information. My question is how to construct primitive cell information given chemical unit cell information? It seems VESTA can do this job, so a related question is how to set the input file for VESTA based on the chemical unit cell information. Thanks!
 
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Thank you very much! This really helps.
 
If I understand correctly, you want to generate all symmetry equivalent positions from the single Wyckoff position usually reported in crystallography papers?
These are listed, for each space group, in the International Tables for Crystallography. The same information can also be found on the Bilbao Crystallographic Server.

http://www.cryst.ehu.es/

Beware that sometimes there are two possible choices of the origin.
 

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