data_ZnBi2As
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   5.21
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   ZnBi2As
_chemical_formula_sum   'Zn1 Bi2 As1'
_cell_volume   99.98
_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
  Zn  Zn3  1  0.0  0.0  0.0  1.0
  Bi  Bi1  1  0.84  0.84  0.84  1.0
  Bi  Bi2  1  0.53  0.53  0.53  1.0
  As  As0  1  0.68  0.68  0.68  1.0

data_ZnBi2As
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   12.76
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   ZnBi2As
_chemical_formula_sum   'Zn3 Bi6 As3'
_cell_volume   299.94
_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
  Zn  Zn0  3  0.0  0.0  0.0  1.0
  Bi  Bi1  3  0.0  0.0  0.16  1.0
  Bi  Bi2  3  0.0  0.0  0.47  1.0
  As  As3  3  0.0  0.0  0.32  1.0

Zn Bi Bi As
ZnBi2As crystallizes in the trigonal R3m space group. Zn(1) is bonded to one Bi(1) and three equivalent As(1) atoms to form distorted ZnBiAs3 trigonal pyramids that share  a cornercorner with one As(1)Zn3Bi2 trigonal bipyramid and corners with six equivalent Zn(1)BiAs3 trigonal pyramids. The Zn(1)-Bi(1) bond length is 2.02 Å. All Zn(1)-As(1) bond lengths are 3.02 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a linear geometry to one Zn(1) and one As(1) atom. The Bi(1)-As(1) bond length is 2.02 Å. In the second Bi site, Bi(2) is bonded in a single-bond geometry to one As(1) atom. The Bi(2)-As(1) bond length is 2.02 Å. As(1) is bonded to three equivalent Zn(1), one Bi(1), and one Bi(2) atom to form distorted AsZn3Bi2 trigonal bipyramids that share corners with six equivalent As(1)Zn3Bi2 trigonal bipyramids and  a cornercorner with one Zn(1)BiAs3 trigonal pyramid.