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Mag cif update para 6 #55

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Dec 1, 2023
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55 changes: 27 additions & 28 deletions cif_mag.dic
Original file line number Diff line number Diff line change
Expand Up @@ -2893,31 +2893,30 @@ save_
save_space_group_magn.ssg_name

_definition.id '_space_group_magn.ssg_name'
_definition.update 2016-10-10
_description.text
;
The Belov-Neronova-Smirnova (BNS) symbol for a magnetic
superspace group (MSSG) is based on the symbol of the
non-magnetic superspace group (SSG) obtained by eliminating all
time-reversed operators from the group, as listed in the ISO(3+d)D
tables of Stokes and Campbell. If the magnetic basic space group
(MBSG) is of type-1 or type-3 (also known as type-3a), its BNS symbol
merely replaces that of the basic space-group (BSG). If the MBSG
is of type-2 or type-4 (also known as type-3b), an additional
phase-shift symbol associated with the time-reversal generator is added
to each modulation vector. If the MBSG is of type-4, the BNS
symbol of the MSSG is further modified to explicitly show the
time-reversal generator (1') at the end, and the anti-centering
subscript is moved from the lattice symbol to the 1' so as to
clearly indicate the fractional external-space translation of
this generator.
The examples are based on SSG 47.1.9.3 Pmmm(0,0,g)ss0 in (3+1)D.
_definition.update 2023-06-01
_description.text
;
The symbol for a magnetic superspace group (MSSG) is based on the UNI
symbol of the basic magnetic space group (BMSG), realized in the limit
that all modulation amplitudes go to zero, and on the ISO(3+D) symbol
of the corresponding non-magnetic superspace group (SSG). The
corresponding SSG symbol is obtained by removing the time-reversal from
each time-reversed operation of a type-1 or type-2 MSSG, or by eliminating
all time-reversed operations for a type-3 or type-4 MSSG. For a type-1
or type-3 MSSG, the MSSG symbol is obtained from the SSG symbol by
simply replacing the symbol of the non-magnetic basic space group (BSG)
with the UNI symbol of the BMSG. For a type-2 or type-4 MSSG, one must
further communicate each of the modulation phase shifts associated
with the time-reversal generator of the magnetic point group (MPG).
The _space_group_magn.ssg_number tag should always be used as the
unique MSSG identifier rather than relying on the MSSG symbol alone.
The examples are based on SSG 47.1.9.3 Pmmm(0,0,g)ss0 in (3+1)D.

Analogous tags: msCIF:_space_group.ssg_name

Ref: ISO-MAG tables of H.T. Stokes and B.J. Campbell at
http://iso.byu.edu. ISO(3+d)D tables of H.T. Stokes and B.J.
Campbell at http://iso.byu.edu.
Ref: ISO-MAG tables of H.T. Stokes and B.J. Campbell at http://iso.byu.edu.
ISO(3+d)D tables of H.T. Stokes and B.J. Campbell at http://iso.byu.edu.
H.T. Stokes and B.J. Campbell, Acta Cryst. A 78, 364-370 (2022).
;
_name.category_id space_group_magn
_name.object_id ssg_name
Expand All @@ -2933,25 +2932,25 @@ save_space_group_magn.ssg_name
;
type-1 MBSG Pmmm
;
Pmmm1'(0,0,g)ss00
Pmmm.1'(0,0,g)ss00
;
type-2 MBSG Pmmm1', with no basic-cell or
type-2 MBSG Pmmm.1', with no basic-cell or
modulated moments allowed
;
Pmmm1'(0,0,g)ss0s
Pmmm.1'(0,0,g)ss0s
;
type-2 MBSG Pmmm1', with magnetic modulations
type-2 MBSG Pmmm.1', with magnetic modulations
allowed, but not basic-cell moments
;
Pm'm'm(0,0,g)ss0
;
type-3 MBSG Pm'm'm
;
Pmmm1'_a(0,0,g)ss00
Pmmm.1'_a(0,0,g)ss00
;
type-4 MBSG P_ammm with purely external anti-centering
;
Pmmm1'_a(0,0,g)ss0s
Pmmm.1'_a(0,0,g)ss0s
;
type-4 MBSG P_ammm with superspace anti-centering
;
Expand Down
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