data_MgFeSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.93
_cell_length_b   4.93
_cell_length_c   4.93
_cell_angle_alpha   145.08
_cell_angle_beta   123.08
_cell_angle_gamma   68.55
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgFeSi2
_chemical_formula_sum   'Mg1 Fe1 Si2'
_cell_volume   56.63
_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
  Mg  Mg1  1  0.0  0.0  0.0  1.0
  Fe  Fe0  1  0.0  0.0  0.07  1.0
  Si  Si2  1  0.0  0.35  0.82  1.0
  Si  Si3  1  0.48  0.0  0.26  1.0

data_MgFeSi2
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.96
_cell_length_b   4.7
_cell_length_c   4.93
_cell_angle_alpha   118.46
_cell_angle_beta   107.46
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgFeSi2
_chemical_formula_sum   'Mg1 Fe1 Si2'
_cell_volume   56.63
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Fe  Fe1  1  0.93  0.93  0.93  1.0
  Si  Si2  1  0.18  0.53  0.53  1.0
  Si  Si3  1  0.22  0.74  0.22  1.0

Mg Fe Si Si
Mg Fe Si Si 0 1 o o o 0 2 o - - 0 2 o o o 0 2 o o - 0 3 o o o 1 2 o - - 1 2 o o o 1 3 o o o 2 3 - o o 
MgFeSi2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a single-bond geometry to one Fe(1), one Si(1), and one Si(2) atom. The Mg(1)-Fe(1) bond length is 0.36 Å. The Mg(1)-Si(1) bond length is 2.52 Å. The Mg(1)-Si(2) bond length is 1.98 Å. Fe(1) is bonded in a single-bond geometry to one Mg(1) and two equivalent Si(1) atoms. There is one shorter (2.29 Å) and one longer (2.46 Å) Fe(1)-Si(1) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Fe(1), and one Si(2) atom. The Si(1)-Si(2) bond length is 2.21 Å. In the second Si site, Si(2) is bonded in a 1-coordinate geometry to one Mg(1) and one Si(1) atom.