data_global _chemical_name_mineral 'Ice VII' loop_ _publ_author_name 'Kamb B' 'Davis B L' _journal_name_full 'Proceedings of the National Academy of Sciences' _journal_volume 52 _journal_year 1964 _journal_page_first 1433 _journal_page_last 1439 _publ_section_title ; Ice VII, the densest form of ice Note: T = 223 K, P = 2.5 GPa ; _database_code_amcsd 0018369 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'O H2' _cell_length_a 3.30 _cell_length_b 3.30 _cell_length_c 3.30 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 35.937 _exptl_crystal_density_diffrn 1.665 _symmetry_space_group_name_H-M 'P n 3 m' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+z,1/2-x,1/2+y' '-y,z,-x' '1/2+x,1/2-y,1/2+z' '-z,x,-y' '1/2+y,1/2-z,1/2+x' '-x,y,-z' 'x,-z,-y' '1/2-z,1/2+y,1/2+x' 'y,-x,-z' '1/2-x,1/2+z,1/2+y' 'z,-y,-x' '1/2-y,1/2+x,1/2+z' 'x,z,y' '1/2-z,1/2-y,1/2-x' 'y,x,z' '1/2-x,1/2-z,1/2-y' 'z,y,x' '1/2-y,1/2-x,1/2-z' '1/2+z,1/2+x,1/2-y' '-y,-z,x' '1/2+x,1/2+y,1/2-z' '-z,-x,y' '1/2+y,1/2+z,1/2-x' '-x,-y,z' '1/2-z,1/2+x,1/2+y' 'y,-z,-x' '1/2-x,1/2+y,1/2+z' 'z,-x,-y' '1/2-y,1/2+z,1/2+x' 'x,-y,-z' '-x,z,-y' '1/2+z,1/2-y,1/2+x' '-y,x,-z' '1/2+x,1/2-z,1/2+y' '-z,y,-x' '1/2+y,1/2-x,1/2+z' '-x,-z,y' '1/2+z,1/2+y,1/2-x' '-y,-x,z' '1/2+x,1/2+z,1/2-y' '-z,-y,x' '1/2+y,1/2+x,1/2-z' '1/2-z,1/2-x,1/2-y' 'y,z,x' '1/2-x,1/2-y,1/2-z' 'z,x,y' '1/2-y,1/2-z,1/2-x' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy O 0.00000 0.00000 0.00000 1.00000 H 0.17000 0.17000 0.17000 0.50000