data_global
_amcsd_formula_title 'SiO2'
loop_
_publ_author_name
'Boisen M B'
'Gibbs G V'
'Bukowinski M S T'
_journal_name_full 'Physics and Chemistry of Minerals'
_journal_volume 21 
_journal_year 1994
_journal_page_first 269
_journal_page_last 284
_publ_section_title
;
 Framework silica structures generated using simulated annealing
 with a potential energy function based on an H6Si2O7 molecule
 Sample: 18
;
_database_code_amcsd 0007883
_chemical_formula_sum 'Si O2'
_cell_length_a 4.1154
_cell_length_b 4.4201
_cell_length_c 15.5724
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 283.269
_exptl_crystal_density_diffrn      2.818
_symmetry_space_group_name_H-M 'I 21 21 21'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2+x,1/2+y,1/2+z'
  '-x,1/2+y,1/2-z'
  '1/2-x,+y,-z'
  '1/2+x,1/2-y,-z'
  '+x,-y,1/2-z'
  '1/2-x,-y,1/2+z'
  '-x,1/2-y,+z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
Si1   0.00000   0.75000   0.81134
Si2   0.00000   0.75000   0.06175
O1   0.23818   0.56935   0.12709
O2   0.32240   0.00000   0.25000
O3   0.25000   0.05307   0.50000