Differences

This shows you the differences between two versions of the page.

Link to this comparison view

anisotropic_temperature_factors [2012/07/19 15:42]
joulchen
anisotropic_temperature_factors [2020/07/16 11:29]
Line 1: Line 1:
-===== Anisotropic Temperature Factors ===== 
-To refine anisotropically all you need to do is delete "beq @ 0.23" from the end of the site line and type "​adps"​ instead. After one cycle of refinement this line gets replaced by the correct adp macro. In TA all sites are forced to be positive definite by default. ​ If you'd rather let adps go negative then think about why (my preference --- //​[[john.evans@durham.ac.uk|John Evans]] 2009/08/27 17:44//) then try adding the macro below: 
  
-<code topas> ​     macro adp_no_limits 
-{ 
- move_to u11 min = Val - .05; max = Val + .05; 
- move_to u22 min = Val - .05; max = Val + .05; 
- move_to u33 min = Val - .05; max = Val + .05; 
- move_to u12 min = Val - .05; max = Val + .05; 
- move_to u13 min = Val - .05; max = Val + .05; 
- move_to u23 min = Val - .05; max = Val + .05; 
-}</​code>​ 
- 
-Be careful in e.g. multihistogram refinements. ​ Here you can't just use the @ symbol for uij parameter names or they'​ll be different for each histogram. ​ It's always sensible to double check that symmetry restrictions on sites are correct. ​ Try table 8.3.1.1 in International Tables or the table on P104 in Terry Willis'​ text "​Thermal vibrations in crystallography"​. 

Personal Tools