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: 8 ; _database_code_amcsd 0007873 _chemical_formula_sum 'Si O2' _cell_length_a 8.8664 _cell_length_b 4.7482 _cell_length_c 8.7918 _cell_angle_alpha 90 _cell_angle_beta 115.4133 _cell_angle_gamma 90 _cell_volume 334.314 _exptl_crystal_density_diffrn 2.388 _symmetry_space_group_name_H-M 'C 1 2/c 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' '-x,y,1/2-z' '1/2-x,1/2+y,1/2-z' '-x,-y,-z' '1/2-x,1/2-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Si 0.81229 0.12825 0.18687 O1 0.25000 0.25000 0.50000 O2 0.18810 0.62173 0.68770 O3 0.00000 0.00488 0.25000