data_ZnSi2As
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.54
_cell_length_b   4.54
_cell_length_c   4.54
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   ZnSi2As
_chemical_formula_sum   'Zn1 Si2 As1'
_cell_volume   66.22
_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  0.21  0.21  0.21  1.0
  Si  Si1  1  0.61  0.61  0.61  1.0
  Si  Si2  1  0.0  0.0  0.0  1.0
  As  As0  1  0.82  0.82  0.82  1.0

data_ZnSi2As
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.54
_cell_length_b   4.54
_cell_length_c   11.12
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   ZnSi2As
_chemical_formula_sum   'Zn3 Si6 As3'
_cell_volume   198.67
_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  0.79  1.0
  Si  Si1  3  0.0  0.0  0.0  1.0
  Si  Si2  3  0.0  0.0  0.39  1.0
  As  As3  3  0.0  0.0  0.18  1.0

Zn Si Si As
Zn Si Si As 0 2 o o o 0 2 o o + 0 2 + o o 0 2 o + o 0 3 - - o 0 3 - o - 0 3 o - - 0 1 - o o 0 1 o - o 0 1 o o - 1 3 o - o 1 3 - o o 1 3 o o - 1 3 o o o 1 2 o + + 1 2 + o + 1 2 + + o 2 3 - - - 
ZnSi2As crystallizes in the trigonal R3m space group. Zn(1) is bonded in a 7-coordinate geometry to one Si(2), three equivalent Si(1), and three equivalent As(1) atoms. The Zn(1)-Si(2) bond length is 2.35 Å. All Zn(1)-Si(1) bond lengths are 2.71 Å. All Zn(1)-As(1) bond lengths are 2.71 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to three equivalent Zn(1) and one As(1) atom. The Si(1)-As(1) bond length is 2.35 Å. In the second Si site, Si(2) is bonded in a distorted linear geometry to one Zn(1) and one As(1) atom. The Si(2)-As(1) bond length is 2.04 Å. As(1) is bonded in a 5-coordinate geometry to three equivalent Zn(1), one Si(1), and one Si(2) atom.