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: 24 ; _database_code_amcsd 0007889 _chemical_formula_sum 'Si O2' _cell_length_a 4.6409 _cell_length_b 5.2953 _cell_length_c 6.7956 _cell_angle_alpha 111.5060 _cell_angle_beta 93.9553 _cell_angle_gamma 90.7337 _cell_volume 154.874 _exptl_crystal_density_diffrn 2.577 _symmetry_space_group_name_H-M 'P 1' loop_ _space_group_symop_operation_xyz 'x,y,z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Si1 0.38321 0.12156 0.91206 Si2 0.98484 0.05842 0.20981 Si3 0.55103 0.07841 0.51208 Si4 0.85250 0.45631 0.90853 O1 0.25629 0.11061 0.38392 O2 0.23864 0.95996 0.04677 O3 0.46346 0.92752 0.67308 O4 0.80431 0.93313 0.35555 O5 0.17541 0.35115 0.88674 O6 0.84740 0.77974 0.03350 O7 0.67863 0.29388 0.02995 O8 0.68733 0.37481 0.67126