data_Y2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.97
_cell_length_b   6.97
_cell_length_c   6.97
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Y2Si
_chemical_formula_sum   'Y8 Si4'
_cell_volume   338.76
_cell_formula_units_Z   4
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
  Y  Y4  1  0.17  0.66  0.8  1.0
  Y  Y5  1  0.8  0.31  0.17  1.0
  Y  Y6  1  0.66  0.8  0.17  1.0
  Y  Y7  1  0.31  0.17  0.8  1.0
  Y  Y8  1  0.8  0.17  0.66  1.0
  Y  Y9  1  0.17  0.8  0.31  1.0
  Y  Y10  1  0.31  0.31  0.31  1.0
  Y  Y11  1  0.66  0.66  0.66  1.0
  Si  Si0  1  0.49  0.0  0.49  1.0
  Si  Si1  1  0.0  0.49  0.49  1.0
  Si  Si2  1  0.0  0.0  0.0  1.0
  Si  Si3  1  0.49  0.49  0.0  1.0

data_Y2Si
_symmetry_space_group_name_H-M   R3
_cell_length_a   9.86
_cell_length_b   9.86
_cell_length_c   12.07
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Y2Si
_chemical_formula_sum   'Y24 Si12'
_cell_volume   1016.27
_cell_formula_units_Z   12
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
  Y  Y0  9  0.04  0.59  0.76  1.0
  Y  Y1  9  0.11  0.37  0.54  1.0
  Y  Y2  3  0.0  0.0  0.31  1.0
  Y  Y3  3  0.0  0.0  0.66  1.0
  Si  Si4  9  0.01  0.5  0.99  1.0
  Si  Si5  3  0.0  0.0  0.0  1.0

Y Y Y Y Y Y Y Y Si Si Si Si
Y Y Y Y Y Y Y Y Si Si Si Si 0 9 o o o 0 10 o + + 0 11 o o + 0 7 o o o 1 11 o o o 1 10 + o o 1 9 + o o 2 11 o o o 2 8 o + o 2 10 + + o 2 7 o o o 3 10 o o + 3 8 o o o 3 11 o o + 4 8 o o o 4 10 + o + 4 9 + o o 4 7 o o o 5 9 o o o 5 10 o + o 5 8 o + o 6 9 o o o 6 8 o o o 6 11 o o o 7 11 o o + 7 8 o + o 7 9 + o o 
Y2Si crystallizes in the trigonal R3 space group. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded in a trigonal planar geometry to one Si(2) and two Si(1,1) atoms. The Y(1)-Si(2) bond length is 3.02 Å. There is one shorter (2.77 Å) and one longer (2.86 Å) Y(1)-Si(1,1) bond length. In the second Y site, Y(2) is bonded in a trigonal planar geometry to one Si(2) and two Si(1,1) atoms. The Y(2)-Si(2) bond length is 2.86 Å. There is one shorter (2.77 Å) and one longer (2.86 Å) Y(2)-Si(1,1) bond length. In the third Y site, Y(3) is bonded in a trigonal planar geometry to three Si(1,1) atoms. All Y(3)-Si(1,1) bond lengths are 2.77 Å. In the fourth Y site, Y(4) is bonded in a trigonal planar geometry to three Si(1,1) atoms. All Y(4)-Si(1,1) bond lengths are 2.93 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one Y(3), one Y(4), two equivalent Y(1), and two equivalent Y(2) atoms to form distorted corner-sharing SiY6 octahedra. The corner-sharing octahedral tilt angles range from 57-66°. There is one shorter (2.77 Å) and one longer (2.86 Å) Si(1)-Y(2) bond length. In the second Si site, Si(1) is bonded to one Y(3), one Y(4), two equivalent Y(1), and two equivalent Y(2) atoms to form distorted corner-sharing SiY6 octahedra. The corner-sharing octahedral tilt angles range from 57-66°. The Si(1)-Y(4) bond length is 2.93 Å. In the third Si site, Si(2) is bonded to three equivalent Y(1) and three equivalent Y(2) atoms to form distorted corner-sharing SiY6 octahedra. The corner-sharing octahedral tilt angles range from 57-66°. In the fourth Si site, Si(1) is bonded to one Y(3), one Y(4), two equivalent Y(1), and two equivalent Y(2) atoms to form distorted corner-sharing SiY6 octahedra. The corner-sharing octahedral tilt angles range from 57-66°. The Si(1)-Y(3) bond length is 2.77 Å. There is one shorter (2.77 Å) and one longer (2.86 Å) Si(1)-Y(1) bond length.