data_global
_chemical_name_mineral 'Carbon'
loop_
_publ_author_name
'Ownby P D'
'Yang X'
'Liu J'
_journal_name_full 'Journal of the American Ceramic Society'
_journal_volume 75 
_journal_year 1992
_journal_page_first 1876
_journal_page_last 1883
_publ_section_title
;
 Calculated X-ray diffraction data for diamond polytypes
 Note: rhombohedral, 21R structure
 Note: theoretically calculated structure values
;
_database_code_amcsd 0014071
_chemical_formula_sum 'C7'
_cell_length_a 2.5221
_cell_length_b 2.5221
_cell_length_c 43.2450
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 238.227
_exptl_crystal_density_diffrn      3.516
_symmetry_space_group_name_H-M 'R -3 m'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '2/3+x,1/3+y,1/3+z'
  '1/3+x,2/3+y,2/3+z'
  'x,x-y,z'
  '2/3+x,1/3+x-y,1/3+z'
  '1/3+x,2/3+x-y,2/3+z'
  'y,x,-z'
  '2/3+y,1/3+x,1/3-z'
  '1/3+y,2/3+x,2/3-z'
  '-x+y,y,z'
  '2/3-x+y,1/3+y,1/3+z'
  '1/3-x+y,2/3+y,2/3+z'
  '-x,-x+y,-z'
  '2/3-x,1/3-x+y,1/3-z'
  '1/3-x,2/3-x+y,2/3-z'
  '-y,-x,z'
  '2/3-y,1/3-x,1/3+z'
  '1/3-y,2/3-x,2/3+z'
  'x-y,-y,-z'
  '2/3+x-y,1/3-y,1/3-z'
  '1/3+x-y,2/3-y,2/3-z'
  'y,-x+y,-z'
  '2/3+y,1/3-x+y,1/3-z'
  '1/3+y,2/3-x+y,2/3-z'
  '-x+y,-x,z'
  '2/3-x+y,1/3-x,1/3+z'
  '1/3-x+y,2/3-x,2/3+z'
  '-x,-y,-z'
  '2/3-x,1/3-y,1/3-z'
  '1/3-x,2/3-y,2/3-z'
  '-y,x-y,z'
  '2/3-y,1/3+x-y,1/3+z'
  '1/3-y,2/3+x-y,2/3+z'
  'x-y,x,-z'
  '2/3+x-y,1/3+x,1/3-z'
  '1/3+x-y,2/3+x,2/3-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
C1   0.00000   0.00000   0.01786
C2   0.00000   0.00000   0.17262
C3   0.00000   0.00000   0.20833
C4   0.00000   0.00000   0.26786
C5   0.00000   0.00000   0.30357
C6   0.00000   0.00000   0.41071
C7   0.00000   0.00000   0.44643