data_1011023 _chemical_name_systematic 'Dihydrogen oxide' _chemical_name_mineral 'Ice Ih' _chemical_formula_structural 'H2 O' _chemical_formula_sum 'H2 O' _publ_section_title ; A Theory of Water and Ionic Solution, with Particular Reference to Hydrogen and Hydroxyl Ions ; loop_ _publ_author_name 'Bernal, J D' 'Fowler, R H' _journal_name_full 'Journal of Chemical Physics' _journal_coden_ASTM JCPSA6 _journal_volume 1 _journal_year 1933 _journal_page_first 515 _journal_page_last 548 _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 389.8 _cell_formula_units_Z 12 _exptl_crystal_density_meas 0.92 _symmetry_space_group_name_H-M 'P 63 c m' _symmetry_Int_Tables_number 185 _symmetry_cell_setting hexagonal loop_ _symmetry_equiv_pos_as_xyz 'x,y,z' '-y,x-y,z' 'y-x,-x,z' 'y,x,z' 'x-y,-y,z' '-x,y-x,z' '-x,-y,1/2+z' 'y,y-x,1/2+z' 'x-y,x,1/2+z' '-y,-x,1/2+z' 'y-x,y,1/2+z' 'x,x-y,1/2+z' loop_ _atom_type_symbol _atom_type_oxidation_number O2- -2.000 H1+ 1.000 loop_ _atom_site_label _atom_site_type_symbol _atom_site_symmetry_multiplicity _atom_site_Wyckoff_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_attached_hydrogens _atom_site_calc_flag O1 O2- 6 c 0.3333 0. 0.0625 1. 0 d O2 O2- 6 c 0.6667 0. 0.9375 1. 0 d H1 H1+ 6 c 0.3333 0. 0.174 1. 0 d H2 H1+ 6 c 0.438 0. 0.026 1. 0 d H3 H1+ 12 d 0.772 0.105 0.975 1. 0 d