data_global _chemical_name_mineral 'Pigeonite' loop_ _publ_author_name 'Merli M' 'Camara F' _journal_name_full 'European Journal of Mineralogy' _journal_volume 15 _journal_year 2003 _journal_page_first 903 _journal_page_last 911 _publ_section_title ; Topological analysis of the electron density of the clinopyroxene structure by the maximum entropy method: an exploratory study Sample: Dien2 Note: c-cell parameter changed by personal communication with author, Dec 2003 ; _database_code_amcsd 0007019 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'Mg1.85 Ca.15 Si2 O6' _cell_length_a 9.651 _cell_length_b 8.846 _cell_length_c 5.252 _cell_angle_alpha 90 _cell_angle_beta 108.38 _cell_angle_gamma 90 _cell_volume 425.504 _exptl_crystal_density_diffrn 3.171 _symmetry_space_group_name_H-M 'P 1 21/c 1' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,1/2-y,1/2+z' '-x,1/2+y,1/2-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy MgM1 0.25087 0.65380 0.22285 1.00000 MgM2 0.25460 0.01964 0.22660 0.85000 CaM2 0.25841 0.01087 0.20226 0.15000 SiA 0.04238 0.34128 0.28692 1.00000 SiB 0.55079 0.83812 0.23265 1.00000 O1A 0.86656 0.33956 0.17880 1.00000 O1B 0.37434 0.83961 0.12751 1.00000 O2A 0.12118 0.50101 0.32222 1.00000 O2B 0.63168 0.98528 0.38165 1.00000 O3A 0.10512 0.27501 0.60186 1.00000 O3B 0.60461 0.70081 0.46414 1.00000 loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 MgM1 0.00629 0.00653 0.00510 0.00011 0.00159 0.00059 MgM2 0.01058 0.01924 0.00766 0.00418 0.00203 0.00455 CaM2 0.01058 0.01924 0.00766 0.00418 0.00203 0.00455 SiA 0.00439 0.00466 0.00536 -0.00038 0.00218 -0.00052 SiB 0.00491 0.00481 0.00547 -0.00092 0.00206 -0.00075 O1A 0.00447 0.00657 0.00625 -0.00012 0.00095 -0.00014 O1B 0.00535 0.00832 0.00567 -0.00047 0.00234 -0.00077 O2A 0.00804 0.00463 0.00796 -0.00132 0.00253 0.00072 O2B 0.01038 0.00754 0.01399 -0.00322 0.00693 -0.00454 O3A 0.00514 0.01205 0.00830 0.00057 0.00219 0.00593 O3B 0.00557 0.01254 0.00884 0.00102 0.00263 0.00384