data_Sr4TiSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.05
_cell_length_b   7.05
_cell_length_c   7.05
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sr4TiSe
_chemical_formula_sum   'Sr4 Ti1 Se1'
_cell_volume   247.59
_cell_formula_units_Z   1
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  Sr1  1  0.74  0.74  0.23  1.0
  Sr  Sr2  1  0.74  0.23  0.74  1.0
  Sr  Sr3  1  0.23  0.74  0.74  1.0
  Sr  Sr4  1  0.23  0.23  0.23  1.0
  Ti  Ti5  1  0.0  0.0  0.0  1.0
  Se  Se0  1  0.49  0.49  0.49  1.0

data_Sr4TiSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   7.05
_cell_length_b   7.05
_cell_length_c   17.26
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Sr4TiSe
_chemical_formula_sum   'Sr12 Ti3 Se3'
_cell_volume   742.76
_cell_formula_units_Z   3
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  0.0  0.5  0.77  1.0
  Sr  Sr1  3  0.0  0.0  0.77  1.0
  Ti  Ti2  3  0.0  0.0  0.0  1.0
  Se  Se3  3  0.0  0.0  0.51  1.0

Sr Sr Sr Sr Ti Se
Sr Sr Sr Sr Ti Se 0 5 o o o 0 4 + + o 0 3 + o o 0 3 o + o 1 5 o o o 1 4 + o + 1 3 + o o 1 3 o o + 2 4 o + + 2 5 o o o 2 3 o + o 2 3 o o + 3 4 o o o 3 5 - o o 3 5 o - o 3 5 o o - 
Sr4TiSe crystallizes in the trigonal R3m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted linear geometry to two equivalent Sr(2), one Ti(1), and one Se(1) atom. Both Sr(1)-Sr(2) bond lengths are 3.52 Å. The Sr(1)-Ti(1) bond length is 2.64 Å. The Sr(1)-Se(1) bond length is 2.44 Å. In the second Sr site, Sr(2) is bonded to six equivalent Sr(1) and one Ti(1) atom to form distorted corner-sharing SrSr6Ti hexagonal pyramids. The Sr(2)-Ti(1) bond length is 3.99 Å. Ti(1) is bonded in a 4-coordinate geometry to one Sr(2) and three equivalent Sr(1) atoms. Se(1) is bonded in a distorted T-shaped geometry to three equivalent Sr(1) atoms.