data_NaC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.79
_cell_length_b   8.79
_cell_length_c   2.56
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   162.47
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaC2
_chemical_formula_sum   'Na2 C4'
_cell_volume   59.53
_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
  Na  Na4  1  0.34  0.59  0.92  1.0
  Na  Na5  1  0.34  0.41  0.64  1.0
  C  C0  1  0.34  0.24  0.92  1.0
  C  C1  1  0.34  0.76  0.64  1.0
  C  C2  1  0.34  0.67  0.92  1.0
  C  C3  1  0.34  0.33  0.64  1.0

data_NaC2
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.56
_cell_length_b   2.68
_cell_length_c   8.79
_cell_angle_alpha   98.77
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   NaC2
_chemical_formula_sum   'Na2 C4'
_cell_volume   59.53
_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
  Na  Na0  2  0.36  0.59  0.59  1.0
  C  C1  2  0.36  0.24  0.24  1.0
  C  C2  2  0.36  0.67  0.67  1.0

Na Na C C C C