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Twinning dictionary version 1.0
Category TWIN
Name:'_twin_[]'
Definition:
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.
http://www.crystallography.fr/mathcryst/twins.htm .
Example:
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.
_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_sigma
_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
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Type: null
Category: category_overview