data_global _chemical_name_mineral 'Silicon' loop_ _publ_author_name 'Olijnyk H' 'Sikka S K' 'Holzapfel W B' _journal_name_full 'Physics Letters' _journal_volume 103A _journal_year 1984 _journal_page_first 137 _journal_page_last 140 _publ_section_title ; Structural phase transitions in Si and Ge under pressures up to 50 GPa Sample: at P = 43 GPa Note: phase VII, structure stable above 43 GPa ; _database_code_amcsd 0015304 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'Si' _cell_length_a 2.444 _cell_length_b 2.444 _cell_length_c 4.152 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 21.478 _exptl_crystal_density_diffrn 4.343 _symmetry_space_group_name_H-M 'P 63/m m c' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-x+y,1/2+z' 'x,x-y,1/2-z' '-x+y,-x,1/2-z' 'x-y,x,1/2+z' '-y,-x,z' 'y,x,-z' 'y,-x+y,-z' '-y,x-y,z' 'x-y,-y,1/2+z' '-x+y,y,1/2-z' 'x,y,1/2-z' '-x,-y,1/2+z' 'x,x-y,z' '-x,-x+y,-z' 'x-y,x,-z' '-x+y,-x,z' 'y,x,1/2+z' '-y,-x,1/2-z' '-y,x-y,1/2-z' 'y,-x+y,1/2+z' '-x+y,y,z' 'x-y,-y,-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Si 0.33333 0.66667 0.25000