data_global _amcsd_formula_title 'SiO2' loop_ _publ_author_name 'Haines J' 'Leger J M' 'Gorelli F' 'Hanfland M' _journal_name_full 'Physical Review Letters' _journal_volume 87 _journal_year 2001 _journal_page_first 155503 _journal_page_last 155503 _publ_section_title ; Crystalline post-quartz phase in silica at high pressure Sample at ambient conditions ; _database_code_amcsd 0015284 _chemical_formula_sum 'Si O2' _cell_length_a 7.66 _cell_length_b 4.10 _cell_length_c 5.03 _cell_angle_alpha 90 _cell_angle_beta 117.9 _cell_angle_gamma 90 _cell_volume 139.610 _exptl_crystal_density_diffrn 4.288 _symmetry_space_group_name_H-M 'P 1 21/c 1' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,1/2-y,1/2+z' '-x,1/2+y,1/2-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Si1 0.50000 0.00000 0.00000 Si2 0.16600 0.50090 0.96880 O1 0.05350 0.24290 0.65110 O2 0.72080 0.24180 0.18640 O3 0.38730 0.23730 0.65970