data_Ta2FeSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.0
_cell_length_b   3.0
_cell_length_c   6.97
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ta2FeSe
_chemical_formula_sum   'Ta2 Fe1 Se1'
_cell_volume   62.75
_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
  Ta  Ta2  1  0.5  0.5  0.35  1.0
  Ta  Ta3  1  0.5  0.5  0.62  1.0
  Fe  Fe0  1  0.0  0.0  0.0  1.0
  Se  Se1  1  0.0  0.0  0.49  1.0

data_Ta2FeSe
_symmetry_space_group_name_H-M   P4mm
_cell_length_a   3.0
_cell_length_b   3.0
_cell_length_c   6.97
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   99
_chemical_formula_structural   Ta2FeSe
_chemical_formula_sum   'Ta2 Fe1 Se1'
_cell_volume   62.75
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x, z'
  3  '-x, -y, z'
  4  'y, -x, z'
  5  '-x, y, z'
  6  'y, x, z'
  7  'x, -y, z'
  8  '-y, -x, 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
  Ta  Ta0  1  0.5  0.5  0.35  1.0
  Ta  Ta1  1  0.5  0.5  0.62  1.0
  Fe  Fe2  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.0  0.0  0.49  1.0

Ta Ta Fe Se
Ta2FeSe crystallizes in the tetragonal P4mm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 5-coordinate geometry to one Ta(2), four equivalent Fe(1), and four equivalent Se(1) atoms. The Ta(1)-Ta(2) bond length is 1.86 Å. All Ta(1)-Fe(1) bond lengths are 3.25 Å. All Ta(1)-Se(1) bond lengths are 2.32 Å. In the second Ta site, Ta(2) is bonded in a 5-coordinate geometry to one Ta(1), four equivalent Fe(1), and four equivalent Se(1) atoms. All Ta(2)-Fe(1) bond lengths are 3.40 Å. All Ta(2)-Se(1) bond lengths are 2.32 Å. Fe(1) is bonded to four equivalent Ta(1), four equivalent Ta(2), and four equivalent Fe(1) atoms to form a mixture of corner and face-sharing FeTa8Fe4 cuboctahedra. All Fe(1)-Fe(1) bond lengths are 3.00 Å. Se(1) is bonded in a distorted body-centered cubic geometry to four equivalent Ta(1) and four equivalent Ta(2) atoms.