The structure described by SiGe crystallizes in the monoclinic P2_1 space group. There are eight inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one Ge(8), two equivalent Ge(5), and one Si(7) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(4)Si3Ge tetrahedra,  a cornercorner with one Si(4)SiGe3 tetrahedra, corners with two equivalent Ge(2)Si3Ge tetrahedra, corners with two equivalent Ge(1)SiGe3 tetrahedra, corners with three equivalent Ge(3)SiGe3 tetrahedra, and corners with three equivalent Si(3)Si3Ge tetrahedra. In the second Ge site, Ge(2) is bonded to one Ge(8), one Si(7), and two equivalent Si(6) atoms to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(3)SiGe3 tetrahedra,  a cornercorner with one Si(3)Si3Ge tetrahedra, corners with two equivalent Ge(2)Si3Ge tetrahedra, corners with two equivalent Ge(1)SiGe3 tetrahedra, corners with three equivalent Ge(4)Si3Ge tetrahedra, and corners with three equivalent Si(4)SiGe3 tetrahedra. In the third Ge site, Ge(3) is bonded to one Ge(5), one Ge(7), one Ge(8), and one Si(5) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(2)Si3Ge tetrahedra,  a cornercorner with one Si(2)SiGe3 tetrahedra, corners with two equivalent Si(3)Si3Ge tetrahedra, corners with two equivalent Si(4)SiGe3 tetrahedra, corners with three equivalent Ge(1)SiGe3 tetrahedra, and corners with three equivalent Si(1)Si3Ge tetrahedra. In the fourth Ge site, Ge(4) is bonded to one Ge(6), one Si(6), one Si(7), and one Si(8) atom to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(1)SiGe3 tetrahedra,  a cornercorner with one Si(1)Si3Ge tetrahedra, corners with two equivalent Si(3)Si3Ge tetrahedra, corners with two equivalent Si(4)SiGe3 tetrahedra, corners with three equivalent Ge(2)Si3Ge tetrahedra, and corners with three equivalent Si(2)SiGe3 tetrahedra. In the fifth Ge site, Ge(5) is bonded to one Ge(3), two equivalent Ge(1), and one Si(3) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(7)Si3Ge tetrahedra,  a cornercorner with one Si(8)Si3Ge tetrahedra, corners with two equivalent Ge(5)SiGe3 tetrahedra, corners with two equivalent Si(5)Si3Ge tetrahedra, corners with three equivalent Ge(8)SiGe3 tetrahedra, and corners with three equivalent Si(7)SiGe3 tetrahedra. In the sixth Ge site, Ge(6) is bonded to one Ge(4), one Si(4), and two equivalent Si(2) atoms to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(8)SiGe3 tetrahedra,  a cornercorner with one Si(7)SiGe3 tetrahedra, corners with two equivalent Ge(6)Si3Ge tetrahedra, corners with two equivalent Si(6)SiGe3 tetrahedra, corners with three equivalent Ge(7)Si3Ge tetrahedra, and corners with three equivalent Si(8)Si3Ge tetrahedra. In the seventh Ge site, Ge(7) is bonded to one Ge(3), one Si(1), one Si(2), and one Si(4) atom to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(5)SiGe3 tetrahedra,  a cornercorner with one Si(6)SiGe3 tetrahedra, corners with two equivalent Ge(8)SiGe3 tetrahedra, corners with two equivalent Si(8)Si3Ge tetrahedra, corners with three equivalent Ge(6)Si3Ge tetrahedra, and corners with three equivalent Si(5)Si3Ge tetrahedra. In the eighth Ge site, Ge(8) is bonded to one Ge(1), one Ge(2), one Ge(3), and one Si(4) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(6)Si3Ge tetrahedra,  a cornercorner with one Si(5)Si3Ge tetrahedra, corners with two equivalent Ge(7)Si3Ge tetrahedra, corners with two equivalent Si(7)SiGe3 tetrahedra, corners with three equivalent Ge(5)SiGe3 tetrahedra, and corners with three equivalent Si(6)SiGe3 tetrahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one Ge(7), one Si(8), and two equivalent Si(5) atoms to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(4)Si3Ge tetrahedra,  a cornercorner with one Si(4)SiGe3 tetrahedra, corners with two equivalent Si(1)Si3Ge tetrahedra, corners with two equivalent Si(2)SiGe3 tetrahedra, corners with three equivalent Ge(3)SiGe3 tetrahedra, and corners with three equivalent Si(3)Si3Ge tetrahedra. In the second Si site, Si(2) is bonded to one Ge(7), two equivalent Ge(6), and one Si(8) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(3)SiGe3 tetrahedra,  a cornercorner with one Si(3)Si3Ge tetrahedra, corners with two equivalent Si(1)Si3Ge tetrahedra, corners with two equivalent Si(2)SiGe3 tetrahedra, corners with three equivalent Ge(4)Si3Ge tetrahedra, and corners with three equivalent Si(4)SiGe3 tetrahedra. In the third Si site, Si(3) is bonded to one Ge(5), one Si(5), one Si(7), and one Si(8) atom to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(2)Si3Ge tetrahedra,  a cornercorner with one Si(2)SiGe3 tetrahedra, corners with two equivalent Ge(4)Si3Ge tetrahedra, corners with two equivalent Ge(3)SiGe3 tetrahedra, corners with three equivalent Ge(1)SiGe3 tetrahedra, and corners with three equivalent Si(1)Si3Ge tetrahedra. In the fourth Si site, Si(4) is bonded to one Ge(6), one Ge(7), one Ge(8), and one Si(6) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(1)SiGe3 tetrahedra,  a cornercorner with one Si(1)Si3Ge tetrahedra, corners with two equivalent Ge(4)Si3Ge tetrahedra, corners with two equivalent Ge(3)SiGe3 tetrahedra, corners with three equivalent Ge(2)Si3Ge tetrahedra, and corners with three equivalent Si(2)SiGe3 tetrahedra. In the fifth Si site, Si(5) is bonded to one Ge(3), one Si(3), and two equivalent Si(1) atoms to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(8)SiGe3 tetrahedra,  a cornercorner with one Si(7)SiGe3 tetrahedra, corners with two equivalent Ge(5)SiGe3 tetrahedra, corners with two equivalent Si(5)Si3Ge tetrahedra, corners with three equivalent Ge(7)Si3Ge tetrahedra, and corners with three equivalent Si(8)Si3Ge tetrahedra. In the sixth Si site, Si(6) is bonded to one Ge(4), two equivalent Ge(2), and one Si(4) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(7)Si3Ge tetrahedra,  a cornercorner with one Si(8)Si3Ge tetrahedra, corners with two equivalent Ge(6)Si3Ge tetrahedra, corners with two equivalent Si(6)SiGe3 tetrahedra, corners with three equivalent Ge(8)SiGe3 tetrahedra, and corners with three equivalent Si(7)SiGe3 tetrahedra. In the seventh Si site, Si(7) is bonded to one Ge(1), one Ge(2), one Ge(4), and one Si(3) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(6)Si3Ge tetrahedra,  a cornercorner with one Si(5)Si3Ge tetrahedra, corners with two equivalent Ge(8)SiGe3 tetrahedra, corners with two equivalent Si(8)Si3Ge tetrahedra, corners with three equivalent Ge(5)SiGe3 tetrahedra, and corners with three equivalent Si(6)SiGe3 tetrahedra. In the eighth Si site, Si(8) is bonded to one Ge(4), one Si(1), one Si(2), and one Si(3) atom to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(5)SiGe3 tetrahedra,  a cornercorner with one Si(6)SiGe3 tetrahedra, corners with two equivalent Ge(7)Si3Ge tetrahedra, corners with two equivalent Si(7)SiGe3 tetrahedra, corners with three equivalent Ge(6)Si3Ge tetrahedra, and corners with three equivalent Si(5)Si3Ge tetrahedra. is represented by the CIF file [CIF]
data_SiGe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.601
_cell_length_b   11.199
_cell_length_c   11.201
_cell_angle_alpha   89.994
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   702.559
_cell_formula_units_Z   16
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  0.005  0.377  0.998  1.0
  Si  Si1  1  0.995  0.873  0.002  1.0
  Si  Si2  1  0.505  0.623  0.002  1.0
  Si  Si3  1  0.495  0.127  0.998  1.0
  Si  Si4  1  0.005  0.627  0.245  1.0
  Si  Si5  1  0.995  0.123  0.250  1.0
  Si  Si6  1  0.505  0.373  0.755  1.0
  Si  Si7  1  0.495  0.877  0.750  1.0
  Si  Si8  1  0.246  0.503  0.121  1.0
  Si  Si9  1  0.254  0.999  0.627  1.0
  Si  Si10  1  0.746  0.497  0.879  1.0
  Si  Si11  1  0.754  0.001  0.373  1.0
  Si  Si12  1  0.246  0.749  0.371  1.0
  Si  Si13  1  0.254  0.253  0.877  1.0
  Si  Si14  1  0.754  0.747  0.123  1.0
  Si  Si15  1  0.746  0.251  0.629  1.0
  Ge  Ge16  1  0.994  0.373  0.502  1.0
  Ge  Ge17  1  0.006  0.877  0.498  1.0
  Ge  Ge18  1  0.494  0.627  0.498  1.0
  Ge  Ge19  1  0.506  0.123  0.502  1.0
  Ge  Ge20  1  0.995  0.623  0.755  1.0
  Ge  Ge21  1  0.005  0.127  0.750  1.0
  Ge  Ge22  1  0.495  0.377  0.245  1.0
  Ge  Ge23  1  0.505  0.873  0.250  1.0
  Ge  Ge24  1  0.255  0.497  0.629  1.0
  Ge  Ge25  1  0.245  0.001  0.123  1.0
  Ge  Ge26  1  0.755  0.503  0.371  1.0
  Ge  Ge27  1  0.745  0.999  0.877  1.0
  Ge  Ge28  1  0.254  0.751  0.879  1.0
  Ge  Ge29  1  0.246  0.247  0.373  1.0
  Ge  Ge30  1  0.746  0.753  0.627  1.0
  Ge  Ge31  1  0.754  0.249  0.121  1.0
[/CIF]
.
The structure described by SiGe crystallizes in the monoclinic P2_1 space group. There are eight inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one Ge(8), two equivalent Ge(5), and one Si(7) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(4)Si3Ge tetrahedra,  a cornercorner with one Si(4)SiGe3 tetrahedra, corners with two equivalent Ge(2)Si3Ge tetrahedra, corners with two equivalent Ge(1)SiGe3 tetrahedra, corners with three equivalent Ge(3)SiGe3 tetrahedra, and corners with three equivalent Si(3)Si3Ge tetrahedra. In the second Ge site, Ge(2) is bonded to one Ge(8), one Si(7), and two equivalent Si(6) atoms to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(3)SiGe3 tetrahedra,  a cornercorner with one Si(3)Si3Ge tetrahedra, corners with two equivalent Ge(2)Si3Ge tetrahedra, corners with two equivalent Ge(1)SiGe3 tetrahedra, corners with three equivalent Ge(4)Si3Ge tetrahedra, and corners with three equivalent Si(4)SiGe3 tetrahedra. In the third Ge site, Ge(3) is bonded to one Ge(5), one Ge(7), one Ge(8), and one Si(5) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(2)Si3Ge tetrahedra,  a cornercorner with one Si(2)SiGe3 tetrahedra, corners with two equivalent Si(3)Si3Ge tetrahedra, corners with two equivalent Si(4)SiGe3 tetrahedra, corners with three equivalent Ge(1)SiGe3 tetrahedra, and corners with three equivalent Si(1)Si3Ge tetrahedra. In the fourth Ge site, Ge(4) is bonded to one Ge(6), one Si(6), one Si(7), and one Si(8) atom to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(1)SiGe3 tetrahedra,  a cornercorner with one Si(1)Si3Ge tetrahedra, corners with two equivalent Si(3)Si3Ge tetrahedra, corners with two equivalent Si(4)SiGe3 tetrahedra, corners with three equivalent Ge(2)Si3Ge tetrahedra, and corners with three equivalent Si(2)SiGe3 tetrahedra. In the fifth Ge site, Ge(5) is bonded to one Ge(3), two equivalent Ge(1), and one Si(3) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(7)Si3Ge tetrahedra,  a cornercorner with one Si(8)Si3Ge tetrahedra, corners with two equivalent Ge(5)SiGe3 tetrahedra, corners with two equivalent Si(5)Si3Ge tetrahedra, corners with three equivalent Ge(8)SiGe3 tetrahedra, and corners with three equivalent Si(7)SiGe3 tetrahedra. In the sixth Ge site, Ge(6) is bonded to one Ge(4), one Si(4), and two equivalent Si(2) atoms to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(8)SiGe3 tetrahedra,  a cornercorner with one Si(7)SiGe3 tetrahedra, corners with two equivalent Ge(6)Si3Ge tetrahedra, corners with two equivalent Si(6)SiGe3 tetrahedra, corners with three equivalent Ge(7)Si3Ge tetrahedra, and corners with three equivalent Si(8)Si3Ge tetrahedra. In the seventh Ge site, Ge(7) is bonded to one Ge(3), one Si(1), one Si(2), and one Si(4) atom to form GeSi3Ge tetrahedra that share  a cornercorner with one Ge(5)SiGe3 tetrahedra,  a cornercorner with one Si(6)SiGe3 tetrahedra, corners with two equivalent Ge(8)SiGe3 tetrahedra, corners with two equivalent Si(8)Si3Ge tetrahedra, corners with three equivalent Ge(6)Si3Ge tetrahedra, and corners with three equivalent Si(5)Si3Ge tetrahedra. In the eighth Ge site, Ge(8) is bonded to one Ge(1), one Ge(2), one Ge(3), and one Si(4) atom to form GeSiGe3 tetrahedra that share  a cornercorner with one Ge(6)Si3Ge tetrahedra,  a cornercorner with one Si(5)Si3Ge tetrahedra, corners with two equivalent Ge(7)Si3Ge tetrahedra, corners with two equivalent Si(7)SiGe3 tetrahedra, corners with three equivalent Ge(5)SiGe3 tetrahedra, and corners with three equivalent Si(6)SiGe3 tetrahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one Ge(7), one Si(8), and two equivalent Si(5) atoms to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(4)Si3Ge tetrahedra,  a cornercorner with one Si(4)SiGe3 tetrahedra, corners with two equivalent Si(1)Si3Ge tetrahedra, corners with two equivalent Si(2)SiGe3 tetrahedra, corners with three equivalent Ge(3)SiGe3 tetrahedra, and corners with three equivalent Si(3)Si3Ge tetrahedra. In the second Si site, Si(2) is bonded to one Ge(7), two equivalent Ge(6), and one Si(8) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(3)SiGe3 tetrahedra,  a cornercorner with one Si(3)Si3Ge tetrahedra, corners with two equivalent Si(1)Si3Ge tetrahedra, corners with two equivalent Si(2)SiGe3 tetrahedra, corners with three equivalent Ge(4)Si3Ge tetrahedra, and corners with three equivalent Si(4)SiGe3 tetrahedra. In the third Si site, Si(3) is bonded to one Ge(5), one Si(5), one Si(7), and one Si(8) atom to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(2)Si3Ge tetrahedra,  a cornercorner with one Si(2)SiGe3 tetrahedra, corners with two equivalent Ge(4)Si3Ge tetrahedra, corners with two equivalent Ge(3)SiGe3 tetrahedra, corners with three equivalent Ge(1)SiGe3 tetrahedra, and corners with three equivalent Si(1)Si3Ge tetrahedra. In the fourth Si site, Si(4) is bonded to one Ge(6), one Ge(7), one Ge(8), and one Si(6) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(1)SiGe3 tetrahedra,  a cornercorner with one Si(1)Si3Ge tetrahedra, corners with two equivalent Ge(4)Si3Ge tetrahedra, corners with two equivalent Ge(3)SiGe3 tetrahedra, corners with three equivalent Ge(2)Si3Ge tetrahedra, and corners with three equivalent Si(2)SiGe3 tetrahedra. In the fifth Si site, Si(5) is bonded to one Ge(3), one Si(3), and two equivalent Si(1) atoms to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(8)SiGe3 tetrahedra,  a cornercorner with one Si(7)SiGe3 tetrahedra, corners with two equivalent Ge(5)SiGe3 tetrahedra, corners with two equivalent Si(5)Si3Ge tetrahedra, corners with three equivalent Ge(7)Si3Ge tetrahedra, and corners with three equivalent Si(8)Si3Ge tetrahedra. In the sixth Si site, Si(6) is bonded to one Ge(4), two equivalent Ge(2), and one Si(4) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(7)Si3Ge tetrahedra,  a cornercorner with one Si(8)Si3Ge tetrahedra, corners with two equivalent Ge(6)Si3Ge tetrahedra, corners with two equivalent Si(6)SiGe3 tetrahedra, corners with three equivalent Ge(8)SiGe3 tetrahedra, and corners with three equivalent Si(7)SiGe3 tetrahedra. In the seventh Si site, Si(7) is bonded to one Ge(1), one Ge(2), one Ge(4), and one Si(3) atom to form SiSiGe3 tetrahedra that share  a cornercorner with one Ge(6)Si3Ge tetrahedra,  a cornercorner with one Si(5)Si3Ge tetrahedra, corners with two equivalent Ge(8)SiGe3 tetrahedra, corners with two equivalent Si(8)Si3Ge tetrahedra, corners with three equivalent Ge(5)SiGe3 tetrahedra, and corners with three equivalent Si(6)SiGe3 tetrahedra. In the eighth Si site, Si(8) is bonded to one Ge(4), one Si(1), one Si(2), and one Si(3) atom to form SiSi3Ge tetrahedra that share  a cornercorner with one Ge(5)SiGe3 tetrahedra,  a cornercorner with one Si(6)SiGe3 tetrahedra, corners with two equivalent Ge(7)Si3Ge tetrahedra, corners with two equivalent Si(7)SiGe3 tetrahedra, corners with three equivalent Ge(6)Si3Ge tetrahedra, and corners with three equivalent Si(5)Si3Ge tetrahedra. is represented by the CIF file [CIF]
data_SiGe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.601
_cell_length_b   11.199
_cell_length_c   11.201
_cell_angle_alpha   89.994
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   702.559
_cell_formula_units_Z   16
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  0.005  0.377  0.998  1.0
  Si  Si1  1  0.995  0.873  0.002  1.0
  Si  Si2  1  0.505  0.623  0.002  1.0
  Si  Si3  1  0.495  0.127  0.998  1.0
  Si  Si4  1  0.005  0.627  0.245  1.0
  Si  Si5  1  0.995  0.123  0.250  1.0
  Si  Si6  1  0.505  0.373  0.755  1.0
  Si  Si7  1  0.495  0.877  0.750  1.0
  Si  Si8  1  0.246  0.503  0.121  1.0
  Si  Si9  1  0.254  0.999  0.627  1.0
  Si  Si10  1  0.746  0.497  0.879  1.0
  Si  Si11  1  0.754  0.001  0.373  1.0
  Si  Si12  1  0.246  0.749  0.371  1.0
  Si  Si13  1  0.254  0.253  0.877  1.0
  Si  Si14  1  0.754  0.747  0.123  1.0
  Si  Si15  1  0.746  0.251  0.629  1.0
  Ge  Ge16  1  0.994  0.373  0.502  1.0
  Ge  Ge17  1  0.006  0.877  0.498  1.0
  Ge  Ge18  1  0.494  0.627  0.498  1.0
  Ge  Ge19  1  0.506  0.123  0.502  1.0
  Ge  Ge20  1  0.995  0.623  0.755  1.0
  Ge  Ge21  1  0.005  0.127  0.750  1.0
  Ge  Ge22  1  0.495  0.377  0.245  1.0
  Ge  Ge23  1  0.505  0.873  0.250  1.0
  Ge  Ge24  1  0.255  0.497  0.629  1.0
  Ge  Ge25  1  0.245  0.001  0.123  1.0
  Ge  Ge26  1  0.755  0.503  0.371  1.0
  Ge  Ge27  1  0.745  0.999  0.877  1.0
  Ge  Ge28  1  0.254  0.751  0.879  1.0
  Ge  Ge29  1  0.246  0.247  0.373  1.0
  Ge  Ge30  1  0.746  0.753  0.627  1.0
  Ge  Ge31  1  0.754  0.249  0.121  1.0
[/CIF]
.