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# Differences

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adps_with_symmetry_constraints [2018/03/06 02:45] rowlesmr3 created |
adps_with_symmetry_constraints [2018/03/06 02:47] rowlesmr3 |
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Description: Include symmetry constraints with anisotropic displacement parameters | Description: Include symmetry constraints with anisotropic displacement parameters | ||

- | Comment: by default topas (at least in v5-7), doesn't constrain the values of anisotropic displacement parameters according to the site symmetry. Symmetry constraints were taken from [1], which is a reprint of [2]. | + | Comment: by default, Topas (at least in v5-7), doesn't constrain the values of anisotropic displacement parameters according to the site symmetry. Symmetry constraints were taken from [1], which is a reprint of [2]. |

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 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. | ||

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+ | 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. | ||

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References: | References: |