data_MgC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.61
_cell_length_b   4.61
_cell_length_c   5.29
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   147.67
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgC2
_chemical_formula_sum   'Mg2 C4'
_cell_volume   60.09
_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  Mg4  1  0.28  0.26  0.97  1.0
  Mg  Mg5  1  0.28  0.74  0.32  1.0
  C  C0  1  0.28  0.71  0.97  1.0
  C  C1  1  0.28  0.82  0.97  1.0
  C  C2  1  0.28  0.18  0.32  1.0
  C  C3  1  0.28  0.29  0.32  1.0

data_MgC2
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.57
_cell_length_b   4.61
_cell_length_c   5.29
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   106.17
_symmetry_Int_Tables_number   2
_chemical_formula_structural   MgC2
_chemical_formula_sum   'Mg2 C4'
_cell_volume   60.09
_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  0.26  0.26  0.18  1.0
  C  C1  2  0.18  0.18  0.82  1.0
  C  C2  2  0.29  0.29  0.82  1.0

Mg Mg C C C C