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Add new UNI symbols. #54

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121 changes: 121 additions & 0 deletions cif_mag.dic
Original file line number Diff line number Diff line change
Expand Up @@ -2732,6 +2732,71 @@ save_space_group_magn.name_og

save_

save_space_group_magn.name_uni

_definition.id '_space_group_magn.name_UNI'
_definition.update 2023-06-01
_description.text
;
The Unified (UNI) symbol for an MSG is an improvement of the
corresponding BNS symbol, and is therefore associated with a BNS
setting of the MSG, but also captures some essential features of
the OG symbol. See the entries on _space_group_magn.name_BNS and
_space_group_magn.name_OG for more information about those symbols.
Like the BNS symbol, the UNI symbol of an MSG is based on the symbol
of a non-magnetic space group F (for types 1-3) or of an index-2
subgroup D of F (for type4). The UNI symbol of a type-3 MSG is
identical to the corresponding BNS and OG symbols.

The time-reversal group consists of the identity operation 1
and the time-reversal operation 1’. For type-1, type-2, and
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type-4 MSGs, the appropriate generator of the time-reversal group
is always explicitly displayed after the space-group generators
of F, and separated from the generators of F by a dot (".").
Furthermore, for a type-4 MSG, the anti-translation subscript is
attached to the 1’ generator at the end of the UNI symbol rather
than to the lattice symbol at the front, and always conveys an
unambiguous translation.

The complete UNI symbol of a type-4 MSG includes the symbol of
space group F in square brackets at the end. In the extension,
the symbol of F is presented in same BNS setting used for subgroup
D in the main part of the UNI symbol, when possible, or else in a
setting rotated by 45 degrees relative to the BNS setting of D.

The UNI MPG symbol is obtained directly from the truncated UNI MSG
symbol by dropping the lattice symbol at the front, eliminating any
subscripts, and replacing each glide-plane symbols with mirror-plane
symbol "m". The explicit presence of the time-reversal generator at
the end of the UNI symbol of a type-4 MSG makes it clear that the
MPG is of type 2 (grey).

Analogous tags: symCIF:_space_group.name_H-M_ref

Ref: Campbell et al., Acta Cryst. A78, 99–106 (2022).
ISO-MAG tables of H.T. Stokes and B.J. Campbell at http://iso.byu.edu
;
_name.category_id space_group_magn
_name.object_id name_UNI
_type.purpose Encode
_type.source Recorded
_type.container Single
_type.contents Text

loop_
_description_example.case
"P1.1"
"P1.1'"
"P1.1'_c[P1] or P1.1'_c"
"P-1.1"
"P-1.1'"
"P-1'"
"P-1.1'_c[P-1] or P1.1'_c"
"P2.1'_C[C2] or P2.1'_C"
"Ia'-3d'"

save_

save_space_group_magn.number_bns

_definition.id '_space_group_magn.number_BNS'
Expand Down Expand Up @@ -2855,6 +2920,62 @@ save_space_group_magn.point_group_name

save_

save_space_group_magn.point_group_name_uni

_definition.id '_space_group_magn.point_group_name_UNI'
_definition.update 2023-06-01
_description.text
;
Any magnetic point group (MPG) can be constructed by starting
with a non-magnetic point group P, and then by adding a time-reversal
component to some or all or none of its elements. For a
type-1 MPG, M = P, there are no time-reversed elements. For a
type-2 MPG, M = P + P1', there is both a time-reversed and a
non-time-reversed copy of each element in P. For a type-3 MPG,
M = Q + (P - Q)1', there is a subgroup Q of P of index 2 whose
elements are not time reversed, whereas the remaining elements
in P-Q are time reversed.

The time-reversal group consists of the identity operation 1
and the time-reversal operation 1’. The UNI symbol of an MPG is a slight
modification of the earlier H-M MPG symbol, and only differs from
the H-M MPG symbol for type-1 and type2 MPGs, so that
the appropriate generator of the time-reversal group
is always explicitly displayed after the space-group generators
of P, and separated from the generators of P by a dot (".").
For a type-1 MPG or type-2 MPG, the UNI symbol is that of
non-magnetic point group P, followed by ".1" or ".1’", respectively.
For a type-3 MPG, the UNI MPG symbol is that of P with a prime added to each
time-reversed generator.

Analogous tags: symCIF:_space_group.point_group_H-M

Ref: 'Magnetic Group Tables' by D.B. Litvin at
http://www.iucr.org/publ/978-0-9553602-2-0
Campbell et al., Acta Cryst. A78, 99–106 (2022).
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https://doi.org/10.1107/S2053273321012912
https://www.iucr.org/paper?ib5106
;
_name.category_id space_group_magn
_name.object_id point_group_name_UNI
_type.purpose Encode
_type.source Recorded
_type.container Single
_type.contents Text

loop_
_description_example.case
1.1
1.1'
-1.1
-1.1'
-1'
4mm.1
4'm'm
4'mm'

save_

save_space_group_magn.point_group_number

_definition.id '_space_group_magn.point_group_number'
Expand Down
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