The crystal structure described by Mn6Si7 is Frank-Kasper $\mu$ Phase structured and crystallizes in the trigonal R-3m space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to six equivalent Si(2) atoms. In the second Mn site, Mn(2) is bonded in a 16-coordinate geometry to one Mn(3), three equivalent Mn(2), three equivalent Si(1), and nine equivalent Si(2) atoms. In the third Mn site, Mn(3) is bonded in a 8-coordinate geometry to one Mn(2), one Mn(3), and six equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to six equivalent Mn(2) and six equivalent Si(2) atoms to form edge-sharing SiMn6Si6 cuboctahedra. In the second Si site, Si(2) is bonded in a 12-coordinate geometry to two equivalent Mn(1), two equivalent Mn(3), three equivalent Mn(2), one Si(1), and four equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mn6Si7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.850
_cell_length_b   4.850
_cell_length_c   8.409
_cell_angle_alpha   73.238
_cell_angle_beta   73.238
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   161.530
_cell_formula_units_Z   1
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
  Mn  Mn0  1  0.835  0.835  0.496  1.0
  Mn  Mn1  1  0.165  0.165  0.504  1.0
  Mn  Mn2  1  0.662  0.662  0.013  1.0
  Mn  Mn3  1  0.338  0.338  0.987  1.0
  Mn  Mn4  1  0.549  0.549  0.352  1.0
  Mn  Mn5  1  0.451  0.451  0.648  1.0
  Si  Si6  1  0.000  0.000  0.000  1.0
  Si  Si7  1  0.914  0.914  0.749  1.0
  Si  Si8  1  0.422  0.914  0.749  1.0
  Si  Si9  1  0.914  0.422  0.749  1.0
  Si  Si10  1  0.086  0.086  0.251  1.0
  Si  Si11  1  0.578  0.086  0.251  1.0
  Si  Si12  1  0.086  0.578  0.251  1.0
[/CIF]
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The crystal structure described by Mn6Si7 is Frank-Kasper $\mu$ Phase structured and crystallizes in the trigonal R-3m space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to six equivalent Si(2) atoms. In the second Mn site, Mn(2) is bonded in a 16-coordinate geometry to one Mn(3), three equivalent Mn(2), three equivalent Si(1), and nine equivalent Si(2) atoms. In the third Mn site, Mn(3) is bonded in a 8-coordinate geometry to one Mn(2), one Mn(3), and six equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to six equivalent Mn(2) and six equivalent Si(2) atoms to form edge-sharing SiMn6Si6 cuboctahedra. In the second Si site, Si(2) is bonded in a 12-coordinate geometry to two equivalent Mn(1), two equivalent Mn(3), three equivalent Mn(2), one Si(1), and four equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mn6Si7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.850
_cell_length_b   4.850
_cell_length_c   8.409
_cell_angle_alpha   73.238
_cell_angle_beta   73.238
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   161.530
_cell_formula_units_Z   1
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
  Mn  Mn0  1  0.835  0.835  0.496  1.0
  Mn  Mn1  1  0.165  0.165  0.504  1.0
  Mn  Mn2  1  0.662  0.662  0.013  1.0
  Mn  Mn3  1  0.338  0.338  0.987  1.0
  Mn  Mn4  1  0.549  0.549  0.352  1.0
  Mn  Mn5  1  0.451  0.451  0.648  1.0
  Si  Si6  1  0.000  0.000  0.000  1.0
  Si  Si7  1  0.914  0.914  0.749  1.0
  Si  Si8  1  0.422  0.914  0.749  1.0
  Si  Si9  1  0.914  0.422  0.749  1.0
  Si  Si10  1  0.086  0.086  0.251  1.0
  Si  Si11  1  0.578  0.086  0.251  1.0
  Si  Si12  1  0.086  0.578  0.251  1.0
[/CIF]
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