data_SiGe3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.31
_cell_length_b   5.31
_cell_length_c   5.31
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SiGe3
_chemical_formula_sum   'Si2 Ge6'
_cell_volume   149.54
_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  Si6  1  0.65  0.65  0.65  1.0
  Si  Si7  1  0.0  0.0  0.0  1.0
  Ge  Ge0  1  0.33  0.0  0.65  1.0
  Ge  Ge1  1  0.98  0.0  0.65  1.0
  Ge  Ge2  1  0.65  0.33  0.0  1.0
  Ge  Ge3  1  0.65  0.98  0.0  1.0
  Ge  Ge4  1  0.0  0.65  0.98  1.0
  Ge  Ge5  1  0.0  0.65  0.33  1.0

data_SiGe3
_symmetry_space_group_name_H-M   R3
_cell_length_a   7.51
_cell_length_b   7.51
_cell_length_c   9.19
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   SiGe3
_chemical_formula_sum   'Si6 Ge18'
_cell_volume   448.63
_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  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+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  3  0.0  0.0  0.0  1.0
  Si  Si1  3  0.0  0.0  0.65  1.0
  Ge  Ge2  9  0.01  0.67  0.99  1.0
  Ge  Ge3  9  0.1  0.22  0.88  1.0

Si Si Ge Ge Ge Ge Ge Ge
Si Si Ge Ge Ge Ge Ge Ge 0 2 o + o 0 4 o o + 0 7 + o o 0 6 + o o 0 3 o + o 0 5 o o + 1 5 - - o 1 3 - o - 1 6 o - - 2 3 - o o 4 5 o - o 6 7 o o + 
Ge3Si crystallizes in the trigonal R3 space group. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 4-coordinate geometry to two equivalent Ge(2), one Si(1), and one Si(2) atom. There is one shorter (1.84 Å) and one longer (2.53 Å) Ge(1)-Ge(2) bond length. The Ge(1)-Si(1) bond length is 2.53 Å. The Ge(1)-Si(2) bond length is 2.53 Å. In the second Ge site, Ge(2) is bonded in a 1-coordinate geometry to two equivalent Ge(1), one Si(1), and one Si(2) atom. The Ge(2)-Si(1) bond length is 2.53 Å. The Ge(2)-Si(2) bond length is 1.84 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted hexagonal planar geometry to three equivalent Ge(1) and three equivalent Ge(2) atoms. In the second Si site, Si(2) is bonded in a 3-coordinate geometry to three equivalent Ge(1) and three equivalent Ge(2) atoms.