data_global
_chemical_name_mineral 'Cristobalite'
loop_
_publ_author_name
'Matsui M'
'Sato T'
'Funamori N'
_journal_name_full 'American Mineralogist'
_journal_volume 99 
_journal_year 2014
_journal_page_first 184
_journal_page_last 189
_publ_section_title
;
 Crystal structures and stabilities of cristobalite-helium phases at high pressures
 Note: P = 4 GPa
;
_database_code_amcsd 0020171
_chemical_compound_source 'calculated structure'
_chemical_formula_sum 'Si O2 He'
_cell_length_a 9.080
_cell_length_b 9.080
_cell_length_c 9.080
_cell_angle_alpha 31.809
_cell_angle_beta 31.809
_cell_angle_gamma 31.809
_cell_volume 184.735
_exptl_crystal_density_diffrn      2.304
_symmetry_space_group_name_H-M 'R -3 c'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2-x,1/2-z,1/2-y'
  '-z,-x,-y'
  '1/2+y,1/2+x,1/2+z'
  'y,z,x'
  '1/2-z,1/2-y,1/2-x'
  '-x,-y,-z'
  '1/2+x,1/2+z,1/2+y'
  'z,x,y'
  '1/2-y,1/2-x,1/2-z'
  '-y,-z,-x'
  '1/2+z,1/2+y,1/2+x'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
Si   0.56220   0.56220   0.56220
O1   0.50000   0.50000   0.50000
O2   0.85230   0.64770   0.25000
He   0.82340   0.82340   0.82340