data_global
_chemical_name_mineral 'Selenium'
loop_
_publ_author_name
'Cherin P'
'Unger P'
_journal_name_full 'Acta Crystallographica, Section B'
_journal_volume 28 
_journal_year 1972
_journal_page_first 313
_journal_page_last 317
_publ_section_title
;
 Refinement of the crystal structure of alpha-monoclinic Se
 Sample: at T = 26 C
 Note: structure known as alpha phase
;
_database_code_amcsd 0009424
_chemical_compound_source 'Synthetic'
_chemical_formula_sum 'Se'
_cell_length_a 9.054
_cell_length_b 9.083
_cell_length_c 11.601
_cell_angle_alpha 90
_cell_angle_beta 90.81
_cell_angle_gamma 90
_cell_volume 953.942
_exptl_crystal_density_diffrn      4.398
_symmetry_space_group_name_H-M 'P 1 21/n 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2+x,1/2-y,1/2+z'
  '1/2-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
Se1   0.32090   0.48400   0.23620
Se2   0.42540   0.66250   0.35690
Se3   0.31780   0.63760   0.53780
Se4   0.13430   0.81860   0.55290
Se5  -0.08620   0.69040   0.52030
Se6  -0.15650   0.73220   0.32940
Se7  -0.08140   0.52170   0.22900
Se8   0.13010   0.59900   0.13370
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
Se1 0.04950 0.04680 0.05840 0.01110 -0.00770 -0.00190
Se2 0.03870 0.05080 0.07000 -0.01010 -0.00560 -0.00410
Se3 0.04360 0.04970 0.05080 0.00220 -0.01770 0.00300
Se4 0.04480 0.04550 0.05880 -0.00320 -0.01050 -0.00160
Se5 0.04000 0.05670 0.04530 -0.00350 -0.00010 0.00300
Se6 0.03410 0.05270 0.05760 0.01040 -0.01000 0.00340
Se7 0.04810 0.04020 0.04870 -0.00880 -0.00890 0.00290
Se8 0.04860 0.04630 0.04560 0.00260 -0.00600 0.00010