SYSTEM-S INVERT & HFREE


SYSTEM-S TOOLS PLATON HOMEPAGE

INVERSION of the Absolute Structure

Non-centrosymmetric structures may require inversion of the structure in order to refine the correct absolute structure as indicated by the Flack parameter.

Inversion may include change of space group when enantiomeric space group pairs are involved or require special origin shifts.

Clicking on the INVRT button will arrange for inversion of the structure in the next SHELXL refinement cycles by setting up the proper parameters for the MOVE instruction.

When change of space group is implied, e.g. P31 to P32, convertion to (creation of) the new space group is arranged automatically.

Enantiomorphic space group pairs are:

[P41, P43], [P4122, P4322], [P41212, P43212], [P31, P32], [P3121, P3221], [P3112, P3212], [P61, P65], [P62, P64], [P6122, P6522], [P6222, P6422], [P4132, P4332]

Space groups requiring an origin shift

Fdd2, I41, I4122, I41md, I41cd, I-42d, F4132


HFREE

Release all AFIX constraints set with HFIX. This allows for the refinement of previously fixed positional parameters.
18-jan-1999 A.L.Spek