data_MgBiAs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.07
_cell_length_b   5.07
_cell_length_c   5.07
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgBiAs2
_chemical_formula_sum   'Mg1 Bi1 As2'
_cell_volume   92.03
_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
  Mg  Mg3  1  0.0  0.0  0.0  1.0
  Bi  Bi2  1  0.58  0.58  0.58  1.0
  As  As0  1  0.79  0.79  0.79  1.0
  As  As1  1  0.38  0.38  0.38  1.0

data_MgBiAs2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.07
_cell_length_b   5.07
_cell_length_c   12.41
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MgBiAs2
_chemical_formula_sum   'Mg3 Bi3 As6'
_cell_volume   276.08
_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
  Mg  Mg0  3  0.0  0.0  0.0  1.0
  Bi  Bi1  3  0.0  0.0  0.42  1.0
  As  As2  3  0.0  0.0  0.21  1.0
  As  As3  3  0.0  0.0  0.62  1.0

Mg Bi As As
MgBiAs2 is Heusler structured and crystallizes in the trigonal R3m space group. Mg(1) is bonded in a 7-coordinate geometry to three equivalent Bi(1), one As(1), and three equivalent As(2) atoms. All Mg(1)-Bi(1) bond lengths are 3.10 Å. The Mg(1)-As(1) bond length is 2.59 Å. All Mg(1)-As(2) bond lengths are 2.97 Å. Bi(1) is bonded in a 5-coordinate geometry to three equivalent Mg(1), one As(1), and one As(2) atom. The Bi(1)-As(1) bond length is 2.59 Å. The Bi(1)-As(2) bond length is 2.59 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded in a distorted linear geometry to one Mg(1) and one Bi(1) atom. In the second As site, As(2) is bonded to three equivalent Mg(1) and one Bi(1) atom to form distorted corner-sharing AsMg3Bi trigonal pyramids.