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authorThomas White <taw@physics.org>2010-07-07 13:22:06 +0200
committerThomas White <taw@physics.org>2012-02-22 15:26:53 +0100
commitd63f622ba7178d7d46c4718cb7bf5cd5eb6fa57b (patch)
tree2cc4acbb4cbe2452bbe5f4f6d344df0807ab22b0
parente2ebf4b642d74b0181736e358e7ee3f963b9ee76 (diff)
Update doc/symmetry
-rw-r--r--doc/symmetry10
1 files changed, 9 insertions, 1 deletions
diff --git a/doc/symmetry b/doc/symmetry
index 4e6298fb..61bc98e3 100644
--- a/doc/symmetry
+++ b/doc/symmetry
@@ -6,6 +6,13 @@ only understands it when plotting a zone axis pattern). get_hkl does NOT
currently understand symmetry, which means you'll have to expand any molecular
model (the PDB) out to P1 to get the correct results. You can achieve that, for
example, by loading it into Mercury, turning on "Packing", and re-saving.
+Alternatively, using CCP4:
+
+$ echo symgen P63 | pdbset xyzin model.pdb xyzout model-P1.pdb
+
+[ While on this subject, you'll probably also want to include hydrogens in the
+model using something like:
+$ echo HYDROGENS APPEND | hgen xyzin model.pdb xyzout model-with-H.pdb ]
Symmetry definitions are included in src/symmetry.c. Point group definitions
are required for merging and the display of merged results (since merging does
@@ -43,7 +50,8 @@ takes a set of Miller indices, a point group and an index, "n", and returns (by
reference) the indices of the "n"th equivalent reflection. Again, you have to
distinguish between the different Wyckoff positions. Lists of equivalent
reflection, grouped according to Wyckoff symbol, can also be found in the
-International Tables.
+International Tables. get_equiv() should return the original indices as the
+first set of equivalent indices, i.e. when idx=0.
It's not normally necessary to write an individual table of equivalents for each
Wyckoff position, because many positions are just "truncated" sub-classes of