-
Notifications
You must be signed in to change notification settings - Fork 3
/
Copy pathcif_twin.dic
1187 lines (1014 loc) · 41.7 KB
/
cif_twin.dic
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
#\#CIF_2.0
##############################################################################
# #
# CIF Twinning Dictionary #
# #
# This dictionary contains names and definitions of twinning data items #
# recognized by the International Union of Crystallography for the exchange #
# of data between laboratories and submissions to journals and databases. #
# #
##############################################################################
data_CIF_TWIN
_dictionary.title CIF_TWIN
_dictionary.class Instance
_dictionary.version 3.1.0
_dictionary.date 2024-11-29
_dictionary.uri
https://github.com/COMCIFS/Twinning_Dictionary/blob/main/cif_twin.dic
_dictionary.ddl_conformance 4.2.0
_dictionary.namespace CifCore
_description.text
;
The DICTIONARY group defines the data items used to specify
the twinning aspects of crystals in a crystallographic study.
;
save_TWIN_GROUP
_definition.id TWIN_GROUP
_definition.scope Category
_definition.class Head
_definition.update 2024-05-15
_description.text
;
The TWIN_GROUP data items describe atomic information
used in crystallographic structure studies.
;
_name.category_id CIF_TWIN
_name.object_id TWIN_GROUP
_import.get
[
{'dupl':Ignore 'file':cif_core.dic 'mode':Full 'save':CIF_CORE_HEAD}
]
save_
save_TWIN
_definition.id TWIN
_definition.scope Category
_definition.class Set
_definition.update 2024-11-21
_description.text
;
Data items in the TWIN category record general details about
the nature of the twinning in the sample.
Terminology for twin dataname definitions was taken directly from:
'International Union of Crystallography Commission on Mathematical
and Theoretical Crystallography Research themes: Crystal twinning'
by Massimo Nespolo, February 3, 2009.
https://www.crystallography.fr/mathcryst/twins.htm .
;
_name.category_id TWIN_GROUP
_name.object_id TWIN
_description_example.case
;
_twin.formation_mechanism gt
_twin.dimensionality triperiodic
_twin.morphology polysynthetic
_twin.special_details
; This is an example of a twin in space group P 32
by the 2 x,x,0 twin operation.
;
loop_
_twin_individual.id
_twin_individual.mass_fraction_refined
_twin_individual.twin_lattice_type
_twin_individual.twin_matrix_11
_twin_individual.twin_matrix_12
_twin_individual.twin_matrix_13
_twin_individual.twin_matrix_21
_twin_individual.twin_matrix_22
_twin_individual.twin_matrix_23
_twin_individual.twin_matrix_31
_twin_individual.twin_matrix_32
_twin_individual.twin_matrix_33
1 0.545(2) ref 1 0 0 0 1 0 0 0 1
2 0.455(2) mt_II 0 1 0 1 0 0 0 0 -1
loop_
_twin_refln.datum_id
_twin_refln.individual_id
_twin_refln.index_h
_twin_refln.index_k
_twin_refln.index_l
_twin_refln.F_squared_calc
_twin_refln.F_squared_meas
_twin_refln.F_squared_meas_su
_twin_refln.include_status
1 1 -1 1 -32 40.17 55.86 7.39 o
1 2 1 -1 32 40.17 55.86 7.39 o
2 1 0 1 -32 125.83 145.63 9.36 o
2 2 1 0 32 125.83 145.63 9.36 o
3 1 1 1 -32 10.33 30.89 7.39 o
3 2 1 1 32 10.33 30.89 7.39 o
4 1 -3 2 -32 28.26 26.84 9.47 o
4 2 2 -3 32 28.26 26.84 9.47 o
5 1 -2 2 -32 4.31 13.21 9.78 o
5 2 2 -2 32 4.31 13.21 9.78 o
6 1 -1 2 -32 10.71 17.48 9.88 o
6 2 2 -1 32 10.71 17.48 9.88 o
7 1 0 2 -32 13.94 37.66 10.51 o
7 2 2 0 32 13.94 37.66 10.51 o
8 1 1 2 -32 58.60 75.41 9.88 o
8 2 2 1 32 58.60 75.41 9.88 o
9 1 -2 3 -32 27.75 41.40 8.01 o
9 2 3 -2 32 27.75 41.40 8.01 o
10 1 -1 3 -32 59.22 65.53 8.11 o
10 2 3 -1 32 59.22 65.53 8.11 o
;
_description_example.detail
;
The twinning example presented here shows twinning by merohedry for
a trigonal crystal system. The simulated space group is P 32 2 1, but
the true space group is P 32. The twin operation chosen is 2: x, x, 0 in
P 32 2 1 corresponding to operation (by rows) 0, 1, 0 / 1, 0, 0 / 0, 0, -1
[see Table 11.2.2.1 of International Tables for Crystallography
(2005), Vol. A].
The TWIN_REFLN loop gives the properties of each diffraction peak
(identified by _twin_refln.datum_id) which is indexed
to both the twin individuals.
In each of the loops shown in this example the first items on a line
are the list reference. While the list reference must be present
in every loop, it is not necessary that it should be declared as the
first item in the loop.
;
save_
save_twin.dimensionality
_definition.id '_twin.dimensionality'
_alias.definition_id '_twin_dimensionality'
_definition.update 2014-06-20
_description.text
;
The degree of overlap between the twin lattices.
Most twin lattice symmetry (TLS) and twin lattice quasi-symmetry (TLQS)
twins as defined by Donnay & Donnay (1974) will be triperiodic.
Reference: Donnay, G. & Donnay, J. D. H. (1974). Can. Mineral. 12, 422-425.
;
_name.category_id twin
_name.object_id dimensionality
_type.purpose State
_type.source Assigned
_type.container Single
_type.contents Code
loop_
_enumeration_set.state
_enumeration_set.detail
triperiodic 'common lattice in three dimensions'
diperiodic 'common lattice in two dimensions'
monoperiodic 'common lattice in one dimension'
save_
save_twin.formation_mechanism
_definition.id '_twin.formation_mechanism'
_alias.definition_id '_twin_formation_mechanism'
_definition.update 2014-06-20
_description.text
;
A description of the method of twin formation.
;
_name.category_id twin
_name.object_id formation_mechanism
_type.purpose State
_type.source Assigned
_type.container Single
_type.contents Code
loop_
_enumeration_set.state
_enumeration_set.detail
gt 'growth twin formed during crystal growth'
tt 'transformation twin formed during phase transition'
mt 'mechanical twin formed as a result of mechanical action'
save_
save_twin.morphology
_definition.id '_twin.morphology'
_alias.definition_id '_twin_morphology'
_definition.update 2014-06-20
_description.text
;
The physical relationship of the different twins to one another.
;
_name.category_id twin
_name.object_id morphology
_type.purpose State
_type.source Assigned
_type.container Single
_type.contents Code
loop_
_enumeration_set.state
_enumeration_set.detail
contact
'separated by a surface'
penetration
'sharing a volume'
simple
'individuals are not repeated'
polysynthetic
'individuals repeat in approximately linear arrangement'
cyclic
'individuals repeat in closed edifice'
save_
save_twin.special_details
_definition.id '_twin.special_details'
_alias.definition_id '_twin_special_details'
_definition.update 2014-06-20
_description.text
;
Information about twinning in the sample not contained in other data items.
;
_name.category_id twin
_name.object_id special_details
_type.purpose Describe
_type.source Recorded
_type.container Single
_type.contents Text
_description_example.case
;
Individuals 3 and 4 arise from form (I) following an
enantiotropic phase transition by sudden cooling in
a cryostat to 173 K.
;
save_
save_TWIN_INDIVIDUAL
_definition.id TWIN_INDIVIDUAL
_definition.scope Category
_definition.class Loop
_definition.update 2014-06-20
_description.text
;
Data items in the TWIN_INDIVIDUAL category describe properties
of each twinned individual, and the symmetry relationships
between the individuals.
;
_name.category_id TWIN
_name.object_id TWIN_INDIVIDUAL
_category_key.name '_twin_individual.id'
save_
save_twin_individual.id
_definition.id '_twin_individual.id'
_alias.definition_id '_twin_individual_id'
_definition.update 2014-06-20
_description.text
;
The unique identifier for this twin individual.
The twin for which _twin_individual.twin_matrix
is the identity matrix is called the reference twin.
It is recommended that the reference twin be labelled '1'.
;
_name.category_id twin_individual
_name.object_id id
_type.purpose Encode
_type.source Assigned
_type.container Single
_type.contents Code
save_
save_twin_individual.mass_fraction_refined
_definition.id '_twin_individual.mass_fraction_refined'
_alias.definition_id '_twin_individual_mass_fraction_refined'
_definition.update 2014-06-20
_description.text
;
The refined mass fraction of this twin individual; the sum
of all mass fractions must equal unity within the limits of
experimental uncertainty.
;
_name.category_id twin_individual
_name.object_id mass_fraction_refined
_type.purpose Measurand
_type.source Derived
_type.container Single
_type.contents Real
_enumeration.range 0:1.0
_units.code none
save_
save_twin_individual.mass_fraction_refined_su
_definition.id '_twin_individual.mass_fraction_refined_su'
_definition.update 2024-11-28
_description.text
;
Standard uncertainty of _twin_individual.mass_fraction_refined.
;
_name.category_id twin_individual
_name.object_id mass_fraction_refined_su
_name.linked_item_id '_twin_individual.mass_fraction_refined'
_units.code none
_import.get [{'file':templ_attr.cif 'save':general_su}]
save_
save_twin_individual.twin_lattice_type
_definition.id '_twin_individual.twin_lattice_type'
_alias.definition_id '_twin_individual_twin_lattice_type'
_definition.update 2014-06-20
_description.text
;
Identification of the symmetry relationships between the
twin lattices as described in International Tables
for Crystallography (2004), Vol. C, Chapter 1.3.
The twin with the identity matrix should be denoted as 'ref'.
;
_name.category_id twin_individual
_name.object_id twin_lattice_type
_type.purpose State
_type.source Assigned
_type.container Single
_type.contents Code
loop_
_enumeration_set.state
_enumeration_set.detail
ref 'reference twin'
mt_I 'merohedral class I (simple inversion)'
mt_II 'merohedral class II (mirror or twofold)'
mt_I+II 'class I and II simultaneously present'
rmt 'reticular merohedral'
pmt 'pseudo-merohedral'
rpmt 'reticular pseudo-merohedral'
nmt 'non-merohedral'
save_
save_twin_individual.twin_matrix
_definition.id '_twin_individual.twin_matrix'
_alias.definition_id '_twin_individual_twin_matrix'
_definition.update 2024-11-29
_description.text
;
The matrix U that multiplies the Miller indices h,k,l
of the reference twin to give the Miller indices h',k',l',
of the twin specified by _twin_individual.id .
| U11 U12 U13 | |h | | h' |
| U21 U22 U23 | |k | = | k' |
| U31 U32 U33 | |l | | l' |
The reference twin must be assigned the identity matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix
_type.purpose Number
_type.source Derived
_type.container Matrix
_type.dimension '[3,3]'
_type.contents Real
_units.code none
_method.purpose Evaluation
_method.expression
;
with t as twin_individual
_twin_individual.twin_matrix =
[[ t.twin_matrix_11, t.twin_matrix_12, t.twin_matrix_13 ],
[ t.twin_matrix_21, t.twin_matrix_22, t.twin_matrix_23 ],
[ t.twin_matrix_31, t.twin_matrix_32, t.twin_matrix_33 ]]
;
save_
save_twin_individual.twin_matrix_11
_definition.id '_twin_individual.twin_matrix_11'
_alias.definition_id '_twin_individual_twin_matrix_11'
_definition.update 2014-06-20
_description.text
;
The [1,1] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_11
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_12
_definition.id '_twin_individual.twin_matrix_12'
_alias.definition_id '_twin_individual_twin_matrix_12'
_definition.update 2014-06-20
_description.text
;
The [1,2] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_12
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_13
_definition.id '_twin_individual.twin_matrix_13'
_alias.definition_id '_twin_individual_twin_matrix_13'
_definition.update 2014-06-20
_description.text
;
The [1,3] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_13
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_21
_definition.id '_twin_individual.twin_matrix_21'
_alias.definition_id '_twin_individual_twin_matrix_21'
_definition.update 2014-06-20
_description.text
;
The [2,1] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_21
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_22
_definition.id '_twin_individual.twin_matrix_22'
_alias.definition_id '_twin_individual_twin_matrix_22'
_definition.update 2014-06-20
_description.text
;
The [2,2] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_22
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_23
_definition.id '_twin_individual.twin_matrix_23'
_alias.definition_id '_twin_individual_twin_matrix_23'
_definition.update 2014-06-20
_description.text
;
The [2,3] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_23
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_31
_definition.id '_twin_individual.twin_matrix_31'
_alias.definition_id '_twin_individual_twin_matrix_31'
_definition.update 2014-06-20
_description.text
;
The [3,1] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_31
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_32
_definition.id '_twin_individual.twin_matrix_32'
_alias.definition_id '_twin_individual_twin_matrix_32'
_definition.update 2014-06-20
_description.text
;
The [3,2] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_32
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_twin_individual.twin_matrix_33
_definition.id '_twin_individual.twin_matrix_33'
_alias.definition_id '_twin_individual_twin_matrix_33'
_definition.update 2014-06-20
_description.text
;
The [3,3] element of the matrix U in _twin_individual.twin_matrix.
;
_name.category_id twin_individual
_name.object_id twin_matrix_33
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Real
_units.code none
save_
save_TWIN_REFLN
_definition.id TWIN_REFLN
_definition.scope Category
_definition.class Loop
_definition.update 2024-11-21
_description.text
;
Items in the TWIN_REFLN category tabulate the calculated values of F^2^
for each peak observed in the diffraction pattern, together with the
measured value of F^2^. The calculated F^2^ for an observed peak is
a weighted sum of the contribution of all the twin components. The
calculated structure factor for each twin contribution can also be given.
;
_name.category_id TWIN
_name.object_id TWIN_REFLN
loop_
_category_key.name
'_twin_refln.datum_id'
'_twin_refln.individual_id'
loop_
_description_example.case
_description_example.detail
;
loop_
_twin_refln.datum_id
_twin_refln.individual_id
_twin_refln.index_h
_twin_refln.index_k
_twin_refln.index_l
_twin_refln.F_squared_meas
_twin_refln.F_squared_meas_su
_twin_refln.include_status
1 1 1 0 0 1.03 0.18 o
1 3 1 0 0 1.03 0.18 o
2 1 2 0 0 1290.01 55.59 o
2 3 2 0 0 1290.01 55.59 o
3 1 3 0 0 2.59 0.42 o
3 3 3 0 0 2.59 0.42 o
4 1 4 0 0 30.98 1.47 o
4 3 4 0 0 30.98 1.47 o
5 1 5 0 0 1.97 0.96 o
5 3 5 0 0 1.97 0.96 o
6 1 6 0 0 1.55 1.14 o
6 2 6 1 2 1.55 1.14 o
6 3 6 0 0 1.55 1.14 o
6 4 6 1 2 1.55 1.14 o
7 1 -6 1 0 0.47 1.06 o
7 2 6 2 2 0.47 1.06 o
;
;
This partial listing describes seven observed diffraction peaks
in a four-individual twin by non-merohedry. The reference individual
is 1. Reflections from the other three individuals 2, 3 and 4 are
present only if these cannot be experimentally separated from the
reference individual.
;
;
loop_
_twin_refln.datum_id
_twin_refln.individual_id
_twin_refln.index_h
_twin_refln.index_k
_twin_refln.index_l
_twin_refln.F_squared_calc
_twin_refln.F_squared_meas
_twin_refln.F_squared_meas_su
_twin_refln.include_status
620 1 1 -6 -3 200.22 207.88 3.35 o
621 1 -1 6 3 225.34 224.15 3.62 o
622 2 -1 6 3 184.64 196.34 3.95 o
623 1 -1 -6 -3 173.28 181.13 3.06 o
624 2 -1 -6 -3 143.40 152.05 2.78 o
625 1 1 6 3 204.45 204.38 4.48 o
625 2 3 -6 1 204.45 204.38 4.48 o
626 1 3 -6 -3 240.97 241.19 3.75 o
626 2 -3 6 3 240.97 241.19 3.75 o
627 1 3 6 3 288.54 281.53 4.31 o
627 2 -3 -6 -3 288.54 281.53 4.31 o
628 1 -5 -6 -3 179.56 176.35 5.36 o
628 2 -3 6 5 179.56 176.35 5.36 o
629 1 5 6 3 235.04 238.84 4.06 o
629 2 -5 -6 -3 235.04 238.84 4.06 o
;
;
This example is taken from Colombo Young & Gladfelter
[Inorg. Chem. (2000), 39, 4621-4624].
Two structures of nitronium tetranitratogallate
are reported as a result of an enantiotropic phase transition.
The higher-temperature phase is in the tetragonal space group I-4,
while the lower-temperature phase is a twin by non-merohedry
in space group I2.
The individuals are enantiomorphic as a result of the phase
transition. In the listing it is clear that reflections with
_twin_refln.datum_id 620-624 do not contain overlapping
reflections, whereas those with _twin_refln.datum_id 625-629
contain contributions from both twins.
;
save_
save_twin_refln.datum_id
_definition.id '_twin_refln.datum_id'
_alias.definition_id '_twin_refln_datum_id'
_definition.update 2014-06-20
_description.text
;
This item serves to identify an observed diffraction peak.
It may include contributions from one or more twin components
and so may appear more than once in the list.
The values of _twin_refln.F_squared_calc and
_twin_refln.F_squared_meas indexed by _twin_refln.datum_id
include the contributions from all the twins.
The diffraction peak is indexed by _twin_refln.index_hkl
referred to the cell of the twin component identified by
_twin_refln.individual_id.
;
_name.category_id twin_refln
_name.object_id datum_id
_type.purpose Key
_type.source Assigned
_type.container Single
_type.contents Code
save_
save_twin_refln.f_squared_calc
_definition.id '_twin_refln.F_squared_calc'
_alias.definition_id '_twin_refln_F_squared_calc'
_definition.update 2014-06-20
_description.text
;
Calculated value for the overall squared structure factors (in
electrons squared for X-ray diffraction) arising from all
the twin contributions to the peak defined by _twin_refln.datum_id.
The total contribution from all twins to a single observed
reflection is modelled according to the method of Pratt, Coyle
and Ibers as follows:
_twin_refln.F_squared_calc = osf * Sum (mf * _refln.F_squared_calc)
where osf is the overall scale factor,
mf is the mass fraction,
and the sum is taken over all the twin components that contribute
to this diffraction peak.
Reference: Pratt, C. S., Coyle, B. A. & Ibers, J. A. (1971).
J. Chem. Soc. A, pp. 2146-2151.
;
_name.category_id twin_refln
_name.object_id F_squared_calc
_type.purpose Measurand
_type.source Derived
_type.container Single
_type.contents Real
_method.purpose Definition
_method.expression
;
If (_diffrn_radiation.probe == "neutron")
_units.code = "femtometre_squared"
Else If (_diffrn_radiation.probe == "electron")
_units.code = "volt_squared"
Else _units.code = "electron_squared"
;
save_
save_twin_refln.f_squared_calc_su
_definition.id '_twin_refln.F_squared_calc_su'
_definition.update 2024-11-21
_description.text
;
Standard uncertainty of _twin_refln.F_squared_calc.
;
_name.category_id twin_refln
_name.object_id F_squared_calc_su
_name.linked_item_id '_twin_refln.F_squared_calc'
_import.get [{'file':templ_attr.cif 'save':general_su}]
_method.purpose Definition
_method.expression
;
If (_diffrn_radiation.probe == "neutron")
_units.code = "femtometre_squared"
Else If (_diffrn_radiation.probe == "electron")
_units.code = "volt_squared"
Else _units.code = "electron_squared"
;
save_
save_twin_refln.f_squared_calc_individual
_definition.id '_twin_refln.F_squared_calc_individual'
_alias.definition_id '_twin_refln_F_squared_calc_individual'
_definition.update 2014-06-20
_description.text
;
Contribution of the twin identified by _twin_refln.individual_id
to _twin_refln.F_squared_calc.
_twin_refln.F_squared_calc_individual = osf * mf * _refln.F_squared_calc
where osf is the overall scale factor, mf is the mass factor.
For X-ray diffraction the units are electrons squared.
;
_name.category_id twin_refln
_name.object_id F_squared_calc_individual
_type.purpose Measurand
_type.source Derived
_type.container Single
_type.contents Real
_method.purpose Definition
_method.expression
;
If (_diffrn_radiation.probe == "neutron")
_units.code = "femtometre_squared"
Else If (_diffrn_radiation.probe == "electron")
_units.code = "volt_squared"
Else _units.code = "electron_squared"
;
save_
save_twin_refln.f_squared_calc_individual_su
_definition.id '_twin_refln.F_squared_calc_individual_su'
_definition.update 2024-11-21
_description.text
;
Standard uncertainty of _twin_refln.F_squared_calc_individual.
;
_name.category_id twin_refln
_name.object_id F_squared_calc_individual_su
_name.linked_item_id '_twin_refln.F_squared_calc_individual'
_import.get [{'file':templ_attr.cif 'save':general_su}]
_method.purpose Definition
_method.expression
;
If (_diffrn_radiation.probe == "neutron")
_units.code = "femtometre_squared"
Else If (_diffrn_radiation.probe == "electron")
_units.code = "volt_squared"
Else _units.code = "electron_squared"
;
save_
save_twin_refln.f_squared_meas
_definition.id '_twin_refln.F_squared_meas'
_alias.definition_id '_twin_refln_F_squared_meas'
_definition.update 2014-06-20
_description.text
;
The observed value F^2^ of the peak referenced by
_twin_refln.datum_id. This is typically the observed peak
intensity after Lorentz and polarization corrections.
;
_name.category_id twin_refln
_name.object_id F_squared_meas
_type.purpose Measurand
_type.source Derived
_type.container Single
_type.contents Real
_method.purpose Definition
_method.expression
;
If (_diffrn_radiation.probe == "neutron")
_units.code = "femtometre_squared"
Else If (_diffrn_radiation.probe == "electron")
_units.code = "volt_squared"
Else _units.code = "electron_squared"
;
save_
save_twin_refln.f_squared_meas_su
_definition.id '_twin_refln.F_squared_meas_su'
loop_
_alias.definition_id
'_twin_refln_F_squared_meas_sigma'
'_twin_refln_F_squared_sigma'
'_twin_refln.F_squared_sigma'
_definition.update 2024-11-21
_description.text
;
Standard uncertainty of _twin_refln.F_squared_meas
;
_name.category_id twin_refln
_name.object_id F_squared_meas_su
_name.linked_item_id '_twin_refln.F_squared_meas'
_type.purpose SU
_type.source Related
_type.container Single
_type.contents Real
_method.purpose Definition
_method.expression
;
If (_diffrn_radiation.probe == "neutron")
_units.code = "femtometre_squared"
Else If (_diffrn_radiation.probe == "electron")
_units.code = "volt_squared"
Else _units.code = "electron_squared"
;
save_
save_twin_refln.include_status
_definition.id '_twin_refln.include_status'
_alias.definition_id '_twin_refln_include_status'
_definition.update 2014-06-20
_description.text
;
A symbol indicating how the reflection is treated during refinement.
;
_name.category_id twin_refln
_name.object_id include_status
_type.purpose State
_type.source Assigned
_type.container Single
_type.contents Code
loop_
_enumeration_set.state
_enumeration_set.detail
o
;
(lower-case letter o for 'observed')
satisfies _refine_ls.d_res_high
satisfies _refine_ls.d_res_low
exceeds _reflns.threshold_expression
;
<
;
satisfies _refine_ls.d_res_high
satisfies _refine_ls.d_res_low
does not exceed _reflns.threshold_expression
;
-
;
systematically absent reflection
;
x
;
unreliable measurement -- not used
;
r
;
removed from the refinement for other reasons
;
h
;
does not satisfy _refine_ls.d_res_high
;
l
;
does not satisfy _refine_ls.d_res_low
;
_enumeration.default o
save_
save_twin_refln.index_h
_definition.id '_twin_refln.index_h'
_alias.definition_id '_twin_refln_index_h'
_definition.update 2014-06-20
_description.text
;
Miller index h in the vector _twin_refln.index_hkl.
;
_name.category_id twin_refln
_name.object_id index_h
_type.purpose Number
_type.source Derived
_type.container Single
_type.contents Integer
_units.code none
save_
save_twin_refln.index_hkl