data_Sr2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.61
_cell_length_b   10.61
_cell_length_c   10.61
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sr2Se
_chemical_formula_sum   'Sr16 Se8'
_cell_volume   844.32
_cell_formula_units_Z   8
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Sr  Sr8  1  0.88  0.63  0.63  1.0
  Sr  Sr9  1  0.63  0.88  0.63  1.0
  Sr  Sr10  1  0.88  0.88  0.88  1.0
  Sr  Sr11  1  0.63  0.63  0.88  1.0
  Sr  Sr12  1  0.25  0.25  0.54  1.0
  Sr  Sr13  1  0.96  0.25  0.25  1.0
  Sr  Sr14  1  0.25  0.96  0.25  1.0
  Sr  Sr15  1  0.25  0.54  0.25  1.0
  Sr  Sr16  1  0.54  0.25  0.25  1.0
  Sr  Sr17  1  0.25  0.25  0.96  1.0
  Sr  Sr18  1  0.5  0.5  0.21  1.0
  Sr  Sr19  1  0.79  0.5  0.5  1.0
  Sr  Sr20  1  0.5  0.79  0.5  1.0
  Sr  Sr21  1  0.5  0.21  0.5  1.0
  Sr  Sr22  1  0.21  0.5  0.5  1.0
  Sr  Sr23  1  0.5  0.5  0.79  1.0
  Se  Se0  1  0.73  0.73  0.27  1.0
  Se  Se1  1  0.27  0.27  0.27  1.0
  Se  Se2  1  0.73  0.27  0.73  1.0
  Se  Se3  1  0.27  0.73  0.73  1.0
  Se  Se4  1  0.02  0.02  0.48  1.0
  Se  Se5  1  0.48  0.48  0.48  1.0
  Se  Se6  1  0.02  0.48  0.02  1.0
  Se  Se7  1  0.48  0.02  0.02  1.0

data_Sr2Se
_symmetry_space_group_name_H-M   R3m
_cell_length_a   10.61
_cell_length_b   10.61
_cell_length_c   25.99
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Sr2Se
_chemical_formula_sum   'Sr48 Se24'
_cell_volume   2532.96
_cell_formula_units_Z   24
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Sr  Sr0  9  0.08  0.17  0.29  1.0
  Sr  Sr1  9  0.1  0.19  0.4  1.0
  Sr  Sr2  9  0.1  0.19  0.65  1.0
  Sr  Sr3  9  0.19  0.1  0.84  1.0
  Sr  Sr4  9  0.19  0.1  0.59  1.0
  Sr  Sr5  3  0.0  0.0  0.12  1.0
  Se  Se6  9  0.03  0.51  0.49  1.0
  Se  Se7  9  0.18  0.36  0.09  1.0
  Se  Se8  3  0.0  0.0  0.52  1.0
  Se  Se9  3  0.0  0.0  0.73  1.0

Sr Sr Sr Sr Sr Sr Sr Sr Sr Sr Sr Sr Sr Sr Sr Sr Se Se Se Se Se Se Se Se
Sr2Se crystallizes in the trigonal R3m space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted square co-planar geometry to one Sr(5), one Sr(6), and two equivalent Sr(1) atoms. The Sr(1)-Sr(5) bond length is 2.93 Å. The Sr(1)-Sr(6) bond length is 2.90 Å. Both Sr(1)-Sr(1) bond lengths are 2.64 Å. In the second Sr site, Sr(2) is bonded in a distorted hexagonal planar geometry to three equivalent Se(1) and three equivalent Se(3) atoms. All Sr(2)-Se(1) bond lengths are 3.44 Å. All Sr(2)-Se(3) bond lengths are 3.42 Å. In the third Sr site, Sr(3) is bonded in a distorted single-bond geometry to one Se(2) atom. The Sr(3)-Se(2) bond length is 2.67 Å. In the fourth Sr site, Sr(4) is bonded in a distorted bent 150 degrees geometry to one Se(2) and two equivalent Se(3) atoms. The Sr(4)-Se(2) bond length is 3.49 Å. Both Sr(4)-Se(3) bond lengths are 2.52 Å. In the fifth Sr site, Sr(5) is bonded in a distorted single-bond geometry to one Sr(1) and one Se(4) atom. The Sr(5)-Se(4) bond length is 2.67 Å. In the sixth Sr site, Sr(6) is bonded in a distorted bent 150 degrees geometry to one Sr(1), one Se(4), and two equivalent Se(1) atoms. The Sr(6)-Se(4) bond length is 3.49 Å. Both Sr(6)-Se(1) bond lengths are 2.52 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to one Sr(2) and two equivalent Sr(6) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to three equivalent Sr(3) and three equivalent Sr(4) atoms. In the third Se site, Se(3) is bonded in a 3-coordinate geometry to one Sr(2) and two equivalent Sr(4) atoms. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to three equivalent Sr(5) and three equivalent Sr(6) atoms.