data_FeC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.52
_cell_length_b   2.52
_cell_length_c   6.46
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeC2
_chemical_formula_sum   'Fe2 C4'
_cell_volume   41.02
_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  0.26  0.0  0.67  1.0
  Fe  Fe5  1  0.0  0.26  0.79  1.0
  C  C0  1  0.0  0.0  0.0  1.0
  C  C1  1  0.26  0.26  0.0  1.0
  C  C2  1  0.26  0.0  0.61  1.0
  C  C3  1  0.0  0.26  0.85  1.0

data_FeC2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.56
_cell_length_b   3.56
_cell_length_c   6.46
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   FeC2
_chemical_formula_sum   'Fe4 C8'
_cell_volume   82.04
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -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
  Fe  Fe0  2  0.0  0.0  0.79  1.0
  Fe  Fe1  2  0.26  0.0  0.67  1.0
  C  C2  4  0.13  0.13  0.0  1.0
  C  C3  2  0.0  0.0  0.85  1.0
  C  C4  2  0.26  0.0  0.61  1.0

Fe Fe C C C C
Fe Fe C C C C 0 4 o o o 1 5 o o o 2 3 o o o 