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Category: category_overview
Data type: null
Examples:
loop_
_atom_site_Fourier_wave_vector_seq_id
_atom_site_Fourier_wave_vector_x
_atom_site_Fourier_wave_vector_description
1 0.568 'First harmonic'
2 1.136 'Second harmonic'
loop_
_atom_site_displace_Fourier_id
_atom_site_displace_Fourier_atom_site_label
_atom_site_displace_Fourier_axis
_atom_site_displace_Fourier_wave_vector_seq_id
Nb1z1 Nb1 z 1
Nb1x2 Nb1 x 2
Nb1y2 Nb1 y 2
S1x1 S1 x 1
S1y1 S1 y 1
S1z1 S1 z 1
S1x2 S1 x 2
S1y2 S1 y 2
S1z2 S1 z 2
Example 1 - extracted from van Smaalen [(1991). J. Phys.: Condens. Matter 3, 1247-1263.]
# NbS2 subsystem has been chosen as reference, i.e. its
# W matrix is the unit matrix.
loop_
_cell_subsystem_code
_cell_subsystem_description
_cell_subsystem_matrix_W_1_1
_cell_subsystem_matrix_W_1_4
_cell_subsystem_matrix_W_2_2
_cell_subsystem_matrix_W_3_3
_cell_subsystem_matrix_W_4_1
_cell_subsystem_matrix_W_4_4
NbS2 '1st subsystem' 1 0 1 1 0 1
LaS '2nd subsystem' 0 1 1 1 1 0
# The modulation wave vectors are referred to the reciprocal basis of each
# subsystem. They are related to the reciprocal basis used to index the whole
# diffraction pattern through the W matrices.
loop_
_atom_site_Fourier_wave_vector_seq_id
_atom_site_Fourier_wave_vector_x
_atom_site_Fourier_wave_vector_z
_atom_site_Fourier_wave_vector_description
1 0.568 0 'First harmonic'
2 1.136 0 'Second harmonic'
3 1.761 0.5 'First harmonic'
4 3.522 1.0 'Second harmonic'
# The modulation coefficients given below are referred to
# each subsystem.
loop_
_atom_site_displace_Fourier_id
_atom_site_displace_Fourier_atom_site_label
_atom_site_displace_Fourier_axis
_atom_site_displace_Fourier_wave_vector_seq_id
Nb1z1_NbS2 Nb1 z 1
Nb1x2_NbS2 Nb1 x 2
Nb1y2_NbS2 Nb1 y 2
S1x1_NbS2 S1 x 1
S1y1_NbS2 S1 y 1
S1z1_NbS2 S1 z 1
S1x2_NbS2 S1 x 2
S1y2_NbS2 S1 y 2
S1z2_NbS2 S1 z 2
La1x3_LaS La1 x 3
La1y3_LaS La1 y 3
La1z3_LaS La1 z 3
La1x4_LaS La1 x 4
La1y4_LaS La1 y 4
La1z4_LaS La1 z 4
S2x3_LaS S2 x 3
S2y3_LaS S2 y 3
S2z3_LaS S2 z 3
S2x4_LaS S2 x 4
S2y4_LaS S2 y 4
S2z4_LaS S2 z 4
Example 2 - extracted from van Smaalen [(1991). J. Phys.: Condens. Matter 3, 1247-1263.]
#
# The same structural data but expressed using a set of linked data blocks
#
# Items concerning the modulated structure of the first
# subsystem
data_LaSNbS2_MOD_NbS2
_audit_block_code 1997-07-24|LaSNbS2|G.M.|_MOD_NbS2
loop_
_audit_link_block_code
_audit_link_block_description
1997-07-24|LaSNbS2|G.M.| 'common experimental and publication data'
1997-07-24|LaSNbS2|G.M.|_REFRNCE 'reference structure (common data)'
1997-07-21|LaSNbS2|G.M.|_MOD 'modulated structure (common data)'
1997-07-24|LaSNbS2|G.M.|_REFRNCE_NbS2 'reference structure (1st subsystem)'
. 'modulated structure (1st subsystem)'
1997-07-24|LaSNbS2|G.M.|_REFRNCE_LaS 'reference structure (2nd subsystem)'
1997-07-21|LaSNbS2|G.M.|_MOD_LaS 'modulated structure (2nd subsystem)'
loop_
_atom_site_Fourier_wave_vector_seq_id
_atom_site_Fourier_wave_vector_x
_atom_site_Fourier_wave_vector_description
1 0.568 'First harmonic'
2 1.136 'Second harmonic'
loop_
_atom_site_displace_Fourier_id
_atom_site_displace_Fourier_atom_site_label
_atom_site_displace_Fourier_axis
_atom_site_displace_Fourier_wave_vector_seq_id
Nb1z1 Nb1 z 1
Nb1x2 Nb1 x 2
Nb1y2 Nb1 y 2
S1x1 S1 x 1
S1y1 S1 y 1
S1z1 S1 z 1
S1x2 S1 x 2
S1y2 S1 y 2
S1z2 S1 z 2
########## End of modulated structure first subsystem data ############
# Items concerning the modulated structure of the second
# subsystem
data_LaSNbS2_MOD_LaS
_audit_block_code 1997-07-24|LaSNbS2|G.M.|_MOD_LaS
loop_
_audit_link_block_code
_audit_link_block_description
1997-07-24|LaSNbS2|G.M.| 'common experimental and publication data'
1997-07-24|LaSNbS2|G.M.|_REFRNCE 'reference structure (common data)'
1997-07-21|LaSNbS2|G.M.|_MOD 'modulated structure (common data)'
1997-07-24|LaSNbS2|G.M.|_REFRNCE_NbS2 'reference structure (1st subsystem)'
1997-07-21|LaSNbS2|G.M.|_MOD_NbS2 'modulated structure (1st subsystem)'
1997-07-24|LaSNbS2|G.M.|_REFRNCE_LaS 'reference structure (2nd subsystem)'
. 'modulated structure (2nd subsystem)'
loop_
_atom_site_Fourier_wave_vector_seq_id
_atom_site_Fourier_wave_vector_x
_atom_site_Fourier_wave_vector_z
_atom_site_Fourier_wave_vector_description
1 1.761 0.5 'First harmonic'
2 3.522 1.0 'Second harmonic'
loop_
_atom_site_displace_Fourier_id
_atom_site_displace_Fourier_atom_site_label
_atom_site_displace_Fourier_axis
_atom_site_displace_Fourier_wave_vector_seq_id
La1x1 La1 x 1
La1y1 La1 y 1
La1z1 La1 z 1
La1x2 La1 x 2
La1y2 La1 y 2
La1z2 La1 z 2
S2x1 S2 x 1
S2y1 S2 y 1
S2z1 S2 z 1
S2x2 S2 x 2
S2y2 S2 y 2
S2z2 S2 z 2
######### End of modulated structure second subsystem data ############
Example 3 - extracted from van Smaalen [(1991). J. Phys.: Condens. Matter 3, 1247-1263.]
_atom_sites_displace_Fourier_axes_description
; a1 and a2 are respectively the long molecular axis
and the axis normal to the mean molecular plane.
;
loop_
_atom_site_displace_Fourier_id
_atom_site_displace_Fourier_atom_site_label
_atom_site_displace_Fourier_axis
_atom_site_displace_Fourier_wave_vector_seq_id
Byphenyl_a1_1 Biphenyl a1 1
Example 4 - extracted from Baudour & Sanquer [(1983). Acta Cryst. B39, 75-84.] Note the entry from the ATOM_SITES_DISPLACE_FOURIER category to describe collective information relating to all the atom sites.
Data items in the ATOM_SITE_DISPLACE_FOURIER category record details about the Fourier components of the displacive modulation of an atom site in a modulated structure. In the case of rigid groups items in this category would only include the translational part of the modulation. The rotational part would appear in a separate list of items belonging to the ATOM_SITE_ROT_FOURIER category. The (in general complex) coefficients of each Fourier component belong to the category ATOM_SITE_DISPLACE_FOURIER_PARAM and are listed separately.