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adps_with_symmetry_constraints [topas wiki]

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adps_with_symmetry_constraints [2024/01/31 11:38] – external edit 127.0.0.1adps_with_symmetry_constraints [2024/02/10 07:58] (current) – external edit 127.0.0.1
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 In all other versions of Topas, use the keyword "adps" to get Topas to insert the correct, symmetry-constrained values. In all other versions of Topas, use the keyword "adps" to get Topas to insert the correct, symmetry-constrained values.
  
-The macros below correspond to Table 4.1 in [1], which refers to Table 4.2, which gives the necessary restrictions for each Wyckoff site in each spacegroup. I'm assuming that a general position in any space group has no constraints on the ADP values. [Note the Willis table may have an error in space group 227. In reference 2 the row for space group 227 is "17 17 18 18 18 9 6 10"; Willis seems to be missing one of the 18's which means Wyckoff sites e, f, g and h are wrong.  Check also International Tables table 8.3.1.1]+The macros below correspond to Table 4.1 in [1], which refers to Table 4.2, which gives the necessary restrictions for each Wyckoff site in each spacegroup. I'm assuming that a general position in any space group has no constraints on the ADP values.
  
  
 The U12, U13, U23 values in the tables are listed as 2*U12, 2*U13, 2*U23, so I think this means that they should be divided by two. But I think this should only be an issue in nos 13-16, where there is a constraint between U22 and U12. The U12, U13, U23 values in the tables are listed as 2*U12, 2*U13, 2*U23, so I think this means that they should be divided by two. But I think this should only be an issue in nos 13-16, where there is a constraint between U22 and U12.
 +
 +Note added by John:
 +Be careful in space group 227 if you're using the Willis table.  It's missing one "18" in the list.  This means that the constraints for Wyckoff sites f onwards are displace one column to the left.  It should read "17 17 18 18 18 9 6 10".
 +
 +The Willis table is {{ :willis_adps.pdf |here}}.  You should always check carefully against (e.g. international tables) when you don't use TOPAS to generate adps.  A program like VESTA will also warn you if they are incorrect.  There is a small number of space-group/Wyckoff site combinations where TOPAS crashes when generating adps so this is sometimes needed.
  
  
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   * [2] [[https://doi.org/10.1107/S0365110X66000318|Peterse, W. J. A. M., and J. H. Palm. 1966. "The Anisotropic Temperature Factor of Atoms in Special Positions." Acta Crystallographica 20 (1): 147-150.]]   * [2] [[https://doi.org/10.1107/S0365110X66000318|Peterse, W. J. A. M., and J. H. Palm. 1966. "The Anisotropic Temperature Factor of Atoms in Special Positions." Acta Crystallographica 20 (1): 147-150.]]
  
-Contributed by: Matthew Rowles; updated by John Evans 31/1/2024+Contributed by: Matthew Rowles
  
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adps_with_symmetry_constraints.1706701097.txt.gz · Last modified: 2024/01/31 11:38 by 127.0.0.1