data_9009853 _chemical_name 'CuSe2' loop_ _publ_author_name 'Heyding R D' 'Murray R M' _journal_name_full "Canadian Journal of Chemistry" _journal_volume 54 _journal_year 1976 _journal_page_first 841 _journal_page_last 848 _publ_section_title ; Crystal structures of Cu1.8Se, Cu3Se2, alpha- and gamma-CuSe, CuSe2, and CuSe2I Note: low-pressure polymorph, marcasite structure ; _chemical_formula_sum 'Cu Se2' _cell_length_a 5.005 _cell_length_b 6.182 _cell_length_c 3.740 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 115.719 _symmetry_space_group_name_H-M 'P n n m' loop_ _symmetry_equiv_pos_as_xyz 'x,y,z' '1/2+x,1/2-y,1/2+z' '1/2-x,1/2+y,1/2-z' '1/2-x,1/2+y,1/2+z' '1/2+x,1/2-y,1/2-z' 'x,y,-z' '-x,-y,z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_Uiso_or_equiv Cu 0.00000 0.00000 0.00000 0.03926 Se 0.18400 0.38500 0.00000 0.02026