data_global _chemical_name_mineral 'Ice Ih' loop_ _publ_author_name 'Bernal J' 'Fowler R' _journal_name_full 'Journal of Chemical Physics' _journal_volume 1 _journal_year 1933 _journal_page_first 515 _journal_page_last 548 _publ_section_title ; A Theory of Water and Ionic Solution, with Particular Reference to Hydrogen and Hydroxyl Ions _cod_database_code 1011023 ; _database_code_amcsd 0017930 _chemical_formula_sum 'O H2' _cell_length_a 7.82 _cell_length_b 7.82 _cell_length_c 7.36 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 389.782 _exptl_crystal_density_diffrn 0.921 _symmetry_space_group_name_H-M 'P 63 c m' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-x+y,z' 'x-y,x,1/2+z' '-y,-x,1/2+z' '-y,x-y,z' 'x-y,-y,z' '-x,-y,1/2+z' 'x,x-y,1/2+z' '-x+y,-x,z' 'y,x,z' 'y,-x+y,1/2+z' '-x+y,y,1/2+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z O1 0.33333 0.00000 0.06250 O2 0.66667 0.00000 0.93750 H1 0.33333 0.00000 0.17400 H2 0.43800 0.00000 0.02600 H3 0.77200 0.10500 0.97500