[IUCr Home Page] [CIF Home Page]

Index

Modulated and composite structures dictionary (msCIF) version 1.0.1

Category ATOM_SITE_DISPLACE_FOURIER

Name:
'_atom_site_displace_Fourier_[]'

Definition:

   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.

Examples:

Example 1 - based on the modulated structure of inorganic misfit layer (LaS)~1.14~NbS~2~ [Smaalen, S. van (1991). J. Phys. Condens. Matter, 3, 1247-1263].
 
     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 2 - based on the modulated structure of inorganic misfit layer (LaS)~1.14~NbS~2~ [Smaalen, S. van (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 3 - based on the modulated structure of inorganic misfit layer (LaS)~1.14~NbS~2~ [Smaalen, S. van (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 4 - extracted from Baudour & Sanquer [Acta Cryst. (1983), B39, 75-84]. Note the entry from the ATOM_SITES_DISPLACE_FOURIER category to describe collective information relating to all the atom sites.
 
     _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



Type: null

Category: category_overview