data_Ba2TaAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.94
_cell_length_b   5.94
_cell_length_c   5.94
_cell_angle_alpha   126.24
_cell_angle_beta   126.24
_cell_angle_gamma   79.49
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ba2TaAs
_chemical_formula_sum   'Ba2 Ta1 As1'
_cell_volume   131.57
_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
  Ba  Ba1  1  0.0  0.68  0.28  1.0
  Ba  Ba2  1  0.68  0.0  0.28  1.0
  Ta  Ta3  1  0.0  0.0  0.56  1.0
  As  As0  1  0.0  0.0  0.0  1.0

data_Ba2TaAs
_symmetry_space_group_name_H-M   Cm
_cell_length_a   7.59
_cell_length_b   7.59
_cell_length_c   5.94
_cell_angle_alpha   90.0
_cell_angle_beta   129.75
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ba2TaAs
_chemical_formula_sum   'Ba4 Ta2 As2'
_cell_volume   263.13
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Ba  Ba0  4  0.06  0.34  0.4  1.0
  Ta  Ta1  2  0.44  0.0  0.44  1.0
  As  As2  2  0.0  0.0  0.0  1.0

Ba Ba Ta As
Ba2TaAs crystallizes in the monoclinic Cm space group. Ba(1) is bonded in a distorted single-bond geometry to one Ta(1) and two equivalent As(1) atoms. The Ba(1)-Ta(1) bond length is 1.62 Å. There is one shorter (3.17 Å) and one longer (3.36 Å) Ba(1)-As(1) bond length. Ta(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ba(1) and one As(1) atom. The Ta(1)-As(1) bond length is 2.58 Å. As(1) is bonded in a 5-coordinate geometry to four equivalent Ba(1) and one Ta(1) atom.