data_MgC
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.66
_cell_length_b   2.63
_cell_length_c   5.58
_cell_angle_alpha   90.0
_cell_angle_beta   100.33
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgC
_chemical_formula_sum   'Mg2 C2'
_cell_volume   52.73
_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  Mg2  1  0.03  0.97  0.49  1.0
  Mg  Mg3  1  0.63  0.66  0.01  1.0
  C  C0  1  0.29  0.97  0.31  1.0
  C  C1  1  0.37  0.66  0.19  1.0

data_MgC
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.63
_cell_length_b   3.66
_cell_length_c   5.58
_cell_angle_alpha   100.33
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   MgC
_chemical_formula_sum   'Mg2 C2'
_cell_volume   52.73
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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  2  0.16  0.2  0.74  1.0
  C  C1  2  0.16  0.46  0.56  1.0

Mg Mg C C