data_Cu2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.82
_cell_length_b   4.82
_cell_length_c   15.68
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cu2Si
_chemical_formula_sum   'Cu16 Si8'
_cell_volume   316.02
_cell_formula_units_Z   8
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
  Cu  Cu0  1  0.0  0.79  0.8  1.0
  Cu  Cu1  1  0.41  0.39  0.88  1.0
  Cu  Cu2  1  0.41  0.39  0.96  1.0
  Cu  Cu3  1  0.0  0.79  0.72  1.0
  Cu  Cu4  1  0.21  0.09  0.84  1.0
  Cu  Cu5  1  0.41  0.0  0.84  1.0
  Cu  Cu6  1  0.79  0.09  0.84  1.0
  Cu  Cu7  1  0.21  0.09  0.0  1.0
  Cu  Cu8  1  0.41  0.0  0.0  1.0
  Cu  Cu9  1  0.79  0.09  0.0  1.0
  Cu  Cu10  1  0.77  0.49  0.76  1.0
  Cu  Cu11  1  0.0  0.37  0.76  1.0
  Cu  Cu12  1  0.23  0.49  0.76  1.0
  Cu  Cu13  1  0.64  0.68  0.92  1.0
  Cu  Cu14  1  0.41  0.81  0.92  1.0
  Cu  Cu15  1  0.18  0.68  0.92  1.0
  Si  Si16  1  0.0  0.0  0.45  1.0
  Si  Si17  1  0.0  0.0  0.24  1.0
  Si  Si18  1  0.0  0.0  0.6  1.0
  Si  Si19  1  0.0  0.0  0.08  1.0
  Si  Si20  1  0.0  0.79  0.4  1.0
  Si  Si21  1  0.41  0.39  0.28  1.0
  Si  Si22  1  0.41  0.39  0.24  1.0
  Si  Si23  1  0.0  0.79  0.44  1.0

data_Cu2Si
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.82
_cell_length_b   4.82
_cell_length_c   15.68
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cu2Si
_chemical_formula_sum   'Cu16 Si8'
_cell_volume   316.02
_cell_formula_units_Z   8
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  Si0  1  0.0  0.0  0.08  1.0
  Si  Si1  1  0.0  0.0  0.24  1.0
  Si  Si2  1  0.0  0.0  0.45  1.0
  Si  Si3  1  0.0  0.0  0.6  1.0
  Cu  Cu4  1  0.0  0.37  0.76  1.0
  Si  Si5  1  0.0  0.79  0.4  1.0
  Si  Si6  1  0.0  0.79  0.44  1.0
  Cu  Cu7  1  0.0  0.79  0.72  1.0
  Cu  Cu8  1  0.0  0.79  0.8  1.0
  Cu  Cu9  1  0.18  0.68  0.92  1.0
  Cu  Cu10  1  0.21  0.09  0.0  1.0
  Cu  Cu11  1  0.21  0.09  0.84  1.0
  Cu  Cu12  1  0.23  0.49  0.76  1.0
  Cu  Cu13  1  0.41  0.0  0.0  1.0
  Cu  Cu14  1  0.41  0.0  0.84  1.0
  Si  Si15  1  0.41  0.39  0.24  1.0
  Si  Si16  1  0.41  0.39  0.28  1.0
  Cu  Cu17  1  0.41  0.39  0.88  1.0
  Cu  Cu18  1  0.41  0.39  0.96  1.0
  Cu  Cu19  1  0.41  0.81  0.92  1.0
  Cu  Cu20  1  0.64  0.68  0.92  1.0
  Cu  Cu21  1  0.77  0.49  0.76  1.0
  Cu  Cu22  1  0.79  0.09  0.0  1.0
  Cu  Cu23  1  0.79  0.09  0.84  1.0

Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Si Si Si Si Si Si Si Si
Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Cu Si Si Si Si Si Si Si Si 0 10 - o o 0 3 o o o 0 4 o + o 1 13 o o o 1 2 o o o 1 4 o o o 2 13 o o o 2 7 o o + 3 10 - o o 3 18 o + o 4 5 o o o 4 6 - o o 5 6 o o o 6 14 o - o 6 11 + o o 7 19 o o o 7 8 o o o 7 9 - o o 8 9 o o o 9 14 o - - 9 19 + o o 10 11 + o o 11 12 o o o 13 14 o o o 14 15 o o o 16 23 o - o 16 18 o o o 17 22 o o o 17 21 o o o 20 23 o o o 21 22 o o o 
Cu2Si crystallizes in the triclinic P1 space group. There are sixteen inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 3-coordinate geometry to one Cu(11), one Cu(4), and one Cu(5) atom. The Cu(1)-Cu(11) bond length is 1.40 Å. The Cu(1)-Cu(4) bond length is 1.15 Å. The Cu(1)-Cu(5) bond length is 1.46 Å. In the second Cu site, Cu(2) is bonded in a 3-coordinate geometry to one Cu(14), one Cu(3), and one Cu(5) atom. The Cu(2)-Cu(14) bond length is 1.40 Å. The Cu(2)-Cu(3) bond length is 1.15 Å. The Cu(2)-Cu(5) bond length is 1.46 Å. In the third Cu site, Cu(3) is bonded in a 3-coordinate geometry to one Cu(14), one Cu(2), and one Cu(8) atom. The Cu(3)-Cu(14) bond length is 1.40 Å. The Cu(3)-Cu(8) bond length is 1.46 Å. In the fourth Cu site, Cu(4) is bonded in a distorted single-bond geometry to one Cu(1), one Cu(11), and one Si(3) atom. The Cu(4)-Cu(11) bond length is 1.40 Å. The Cu(4)-Si(3) bond length is 2.15 Å. In the fifth Cu site, Cu(5) is bonded in a 3-coordinate geometry to one Cu(1), one Cu(2), and one Cu(6) atom. The Cu(5)-Cu(6) bond length is 1.26 Å. In the sixth Cu site, Cu(6) is bonded in a 3-coordinate geometry to one Cu(15), one Cu(5), and one Cu(7) atom. The Cu(6)-Cu(15) bond length is 1.55 Å. The Cu(6)-Cu(7) bond length is 1.67 Å. In the seventh Cu site, Cu(7) is bonded in a 2-coordinate geometry to one Cu(10), one Cu(12), and one Cu(6) atom. The Cu(7)-Cu(10) bond length is 2.50 Å. The Cu(7)-Cu(12) bond length is 1.73 Å. In the eighth Cu site, Cu(8) is bonded in a 3-coordinate geometry to one Cu(10), one Cu(3), one Cu(9), and one Si(4) atom. The Cu(8)-Cu(10) bond length is 1.99 Å. The Cu(8)-Cu(9) bond length is 1.26 Å. The Cu(8)-Si(4) bond length is 1.48 Å. In the ninth Cu site, Cu(9) is bonded in a 3-coordinate geometry to one Cu(10), one Cu(15), and one Cu(8) atom. The Cu(9)-Cu(10) bond length is 1.67 Å. The Cu(9)-Cu(15) bond length is 1.55 Å. In the tenth Cu site, Cu(10) is bonded in a 7-coordinate geometry to one Cu(14), one Cu(15), one Cu(16), one Cu(7), one Cu(8), one Cu(9), and one Si(4) atom. The Cu(10)-Cu(14) bond length is 2.12 Å. The Cu(10)-Cu(15) bond length is 2.07 Å. The Cu(10)-Cu(16) bond length is 2.81 Å. The Cu(10)-Si(4) bond length is 1.75 Å. In the eleventh Cu site, Cu(11) is bonded in a 3-coordinate geometry to one Cu(1), one Cu(12), and one Cu(4) atom. The Cu(11)-Cu(12) bond length is 1.51 Å. In the twelfth Cu site, Cu(12) is bonded in a distorted single-bond geometry to one Cu(11), one Cu(13), and one Cu(7) atom. The Cu(12)-Cu(13) bond length is 0.96 Å. In the thirteenth Cu site, Cu(13) is bonded in a single-bond geometry to one Cu(12) atom. In the fourteenth Cu site, Cu(14) is bonded in a 3-coordinate geometry to one Cu(10), one Cu(15), one Cu(2), and one Cu(3) atom. The Cu(14)-Cu(15) bond length is 1.51 Å. In the fifteenth Cu site, Cu(15) is bonded in a 1-coordinate geometry to one Cu(10), one Cu(14), one Cu(16), one Cu(6), and one Cu(9) atom. The Cu(15)-Cu(16) bond length is 0.96 Å. In the sixteenth Cu site, Cu(16) is bonded in a single-bond geometry to one Cu(10) and one Cu(15) atom. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 3-coordinate geometry to one Si(3), one Si(5), and one Si(8) atom. The Si(1)-Si(3) bond length is 2.50 Å. The Si(1)-Si(5) bond length is 1.27 Å. The Si(1)-Si(8) bond length is 1.04 Å. In the second Si site, Si(2) is bonded in a 5-coordinate geometry to one Si(4), one Si(5), one Si(6), and two equivalent Si(7) atoms. The Si(2)-Si(4) bond length is 2.50 Å. The Si(2)-Si(5) bond length is 2.74 Å. The Si(2)-Si(6) bond length is 2.08 Å. There is one shorter (1.94 Å) and one longer (2.88 Å) Si(2)-Si(7) bond length. In the third Si site, Si(3) is bonded in a 2-coordinate geometry to one Cu(4) and one Si(1) atom. In the fourth Si site, Si(4) is bonded in a 3-coordinate geometry to one Cu(10), one Cu(8), and one Si(2) atom. In the fifth Si site, Si(5) is bonded in a distorted single-bond geometry to one Si(1), one Si(2), and one Si(8) atom. The Si(5)-Si(8) bond length is 0.70 Å. In the sixth Si site, Si(6) is bonded in a single-bond geometry to one Si(2) and one Si(7) atom. The Si(6)-Si(7) bond length is 0.70 Å. In the seventh Si site, Si(7) is bonded in a single-bond geometry to one Si(6) and two equivalent Si(2) atoms. In the eighth Si site, Si(8) is bonded in an L-shaped geometry to one Si(1) and one Si(5) atom.