data_MnAlSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.69
_cell_length_b   2.69
_cell_length_c   7.43
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MnAlSi2
_chemical_formula_sum   'Mn1 Al1 Si2'
_cell_volume   53.64
_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  Mn1  1  0.34  0.34  0.64  1.0
  Al  Al0  1  0.0  0.0  0.89  1.0
  Si  Si2  1  0.0  0.0  0.24  1.0
  Si  Si3  1  0.34  0.34  0.81  1.0

data_MnAlSi2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.8
_cell_length_b   3.8
_cell_length_c   7.43
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MnAlSi2
_chemical_formula_sum   'Mn2 Al2 Si4'
_cell_volume   107.27
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  2  0.34  0.0  0.64  1.0
  Al  Al1  2  0.0  0.0  0.89  1.0
  Si  Si2  2  0.0  0.0  0.24  1.0
  Si  Si3  2  0.34  0.0  0.81  1.0

Mn Al Si Si
Mn Al Si Si 0 3 o o o 1 3 o o o 1 2 o o + 2 2 + o o 2 2 o + o 
MnAlSi2 crystallizes in the monoclinic Cm space group. Mn(1) is bonded in a single-bond geometry to one Si(1) and one Si(2) atom. The Mn(1)-Si(1) bond length is 3.28 Å. The Mn(1)-Si(2) bond length is 1.26 Å. Al(1) is bonded in a distorted single-bond geometry to one Si(1) and one Si(2) atom. The Al(1)-Si(1) bond length is 2.63 Å. The Al(1)-Si(2) bond length is 1.41 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to one Mn(1), one Al(1), and four equivalent Si(1) atoms. All Si(1)-Si(1) bond lengths are 2.69 Å. In the second Si site, Si(2) is bonded in a 2-coordinate geometry to one Mn(1) and one Al(1) atom.