data_Si2Ag
_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   Si2Ag
_chemical_formula_sum   'Si4 Ag2'
_cell_volume   100.2
_cell_formula_units_Z   2
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
  Si  Si2  1  0.76  0.76  0.61  1.0
  Si  Si3  1  0.61  0.76  0.76  1.0
  Si  Si4  1  0.76  0.61  0.76  1.0
  Si  Si5  1  0.61  0.61  0.61  1.0
  Ag  Ag0  1  0.0  0.0  0.0  1.0
  Ag  Ag1  1  0.84  0.84  0.84  1.0

data_Si2Ag
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   12.77
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Si2Ag
_chemical_formula_sum   'Si12 Ag6'
_cell_volume   300.59
_cell_formula_units_Z   6
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
  Si  Si0  9  0.1  0.05  0.29  1.0
  Si  Si1  3  0.0  0.0  0.39  1.0
  Ag  Ag2  3  0.0  0.0  0.0  1.0
  Ag  Ag3  3  0.0  0.0  0.16  1.0

Si Si Si Si Ag Ag
Si Si Si Si Ag Ag 0 2 o o o 0 1 o o o 0 3 o o o 0 5 o o o 1 2 o o o 1 3 o o o 1 5 o o o 2 3 o o o 2 5 o o o 4 5 - - - 
AgSi2 crystallizes in the trigonal R3m space group. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a distorted tetrahedral geometry to one Ag(2) and three equivalent Si(1) atoms. The Ag(1)-Ag(2) bond length is 2.00 Å. All Ag(1)-Si(1) bond lengths are 2.60 Å. In the second Ag site, Ag(2) is bonded in a 4-coordinate geometry to one Ag(1) and three equivalent Si(1) atoms. All Ag(2)-Si(1) bond lengths are 1.73 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 5-coordinate geometry to one Ag(1), one Ag(2), one Si(2), and two equivalent Si(1) atoms. The Si(1)-Si(2) bond length is 1.42 Å. Both Si(1)-Si(1) bond lengths are 0.82 Å. In the second Si site, Si(2) is bonded in a 3-coordinate geometry to three equivalent Si(1) atoms.