data_FeC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.53
_cell_length_b   3.53
_cell_length_c   4.13
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.57
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeC2
_chemical_formula_sum   'Fe2 C4'
_cell_volume   51.65
_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
  Fe  Fe4  1  0.49  0.78  0.03  1.0
  Fe  Fe5  1  0.49  0.22  0.1  1.0
  C  C0  1  0.17  0.63  0.03  1.0
  C  C1  1  0.81  0.37  0.1  1.0
  C  C2  1  0.81  0.63  0.03  1.0
  C  C3  1  0.17  0.37  0.1  1.0

data_FeC2
_symmetry_space_group_name_H-M   P2/m
_cell_length_a   3.53
_cell_length_b   3.53
_cell_length_c   4.13
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   10
_chemical_formula_structural   FeC2
_chemical_formula_sum   'Fe2 C4'
_cell_volume   51.65
_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, -z'
  4  '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
  Fe  Fe0  2  0.22  0.5  0.03  1.0
  C  C1  4  0.37  0.17  0.03  1.0

Fe Fe C C C C