data_Ag3SI
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.0
_cell_length_b   5.0
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ag3SI
_chemical_formula_sum   'Ag3 S1 I1'
_cell_volume   125.01
_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
  Ag  Ag0  1  0.0  0.0  0.5  1.0
  Ag  Ag1  1  0.0  0.5  0.0  1.0
  Ag  Ag2  1  0.5  0.0  0.0  1.0
  S  S4  1  0.0  0.0  0.0  1.0
  I  I3  1  0.5  0.5  0.5  1.0

data_Ag3SI
_symmetry_space_group_name_H-M   Pm-3m
_cell_length_a   5.0
_cell_length_b   5.0
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   221
_chemical_formula_structural   Ag3SI
_chemical_formula_sum   'Ag3 S1 I1'
_cell_volume   125.01
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-y, x, z'
  4  'y, -x, -z'
  5  '-x, -y, z'
  6  'x, y, -z'
  7  'y, -x, z'
  8  '-y, x, -z'
  9  'x, -y, -z'
  10  '-x, y, z'
  11  '-y, -x, -z'
  12  'y, x, z'
  13  '-x, y, -z'
  14  'x, -y, z'
  15  'y, x, -z'
  16  '-y, -x, z'
  17  'z, x, y'
  18  '-z, -x, -y'
  19  'z, -y, x'
  20  '-z, y, -x'
  21  'z, -x, -y'
  22  '-z, x, y'
  23  'z, y, -x'
  24  '-z, -y, x'
  25  '-z, x, -y'
  26  'z, -x, y'
  27  '-z, -y, -x'
  28  'z, y, x'
  29  '-z, -x, y'
  30  'z, x, -y'
  31  '-z, y, x'
  32  'z, -y, -x'
  33  'y, z, x'
  34  '-y, -z, -x'
  35  'x, z, -y'
  36  '-x, -z, y'
  37  '-y, z, -x'
  38  'y, -z, x'
  39  '-x, z, y'
  40  'x, -z, -y'
  41  '-y, -z, x'
  42  'y, z, -x'
  43  '-x, -z, -y'
  44  'x, z, y'
  45  'y, -z, -x'
  46  '-y, z, x'
  47  'x, -z, y'
  48  '-x, z, -y'
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
  Ag  Ag0  3  0.0  0.0  0.5  1.0
  S  S1  1  0.0  0.0  0.0  1.0
  I  I2  1  0.5  0.5  0.5  1.0

Ag Ag Ag S I
Ag3SI is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. Ag(1) is bonded in a linear geometry to two equivalent S(1) and four equivalent I(1) atoms. Both Ag(1)-S(1) bond lengths are 2.50 Å. All Ag(1)-I(1) bond lengths are 3.54 Å. S(1) is bonded to six equivalent Ag(1) atoms to form SAg6 octahedra that share corners with six equivalent S(1)Ag6 octahedra and faces with eight equivalent I(1)Ag12 cuboctahedra. The corner-sharing octahedra are not tilted. I(1) is bonded to twelve equivalent Ag(1) atoms to form IAg12 cuboctahedra that share corners with twelve equivalent I(1)Ag12 cuboctahedra, faces with six equivalent I(1)Ag12 cuboctahedra, and faces with eight equivalent S(1)Ag6 octahedra.