data_MgSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.02
_cell_length_b   4.22
_cell_length_c   5.7
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgSi
_chemical_formula_sum   'Mg2 Si2'
_cell_volume   72.76
_cell_formula_units_Z   2
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  0.72  1.0
  Mg  Mg1  1  0.51  0.11  0.98  1.0
  Si  Si2  1  0.0  0.0  0.8  1.0
  Si  Si3  1  0.51  0.11  0.9  1.0

data_MgSi
_symmetry_space_group_name_H-M   P2_1/m
_cell_length_a   4.22
_cell_length_b   3.02
_cell_length_c   5.7
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   11
_chemical_formula_structural   MgSi
_chemical_formula_sum   'Mg2 Si2'
_cell_volume   72.76
_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, y+1/2, -z'
  4  'x, -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
  Mg  Mg0  2  0.06  0.25  0.63  1.0
  Si  Si1  2  0.06  0.25  0.55  1.0

Mg Mg Si Si