data_Na2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.73
_cell_length_b   5.73
_cell_length_c   7.85
_cell_angle_alpha   111.45
_cell_angle_beta   111.45
_cell_angle_gamma   39.06
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2Si
_chemical_formula_sum   'Na4 Si2'
_cell_volume   149.91
_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  Na0  1  0.4  0.0  0.09  1.0
  Na  Na1  1  0.73  0.0  0.19  1.0
  Na  Na2  1  0.03  0.0  0.05  1.0
  Na  Na3  1  0.56  0.0  0.67  1.0
  Si  Si4  1  0.09  0.0  0.6  1.0
  Si  Si5  1  0.96  0.0  0.33  1.0

data_Na2Si
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.83
_cell_length_b   5.73
_cell_length_c   7.85
_cell_angle_alpha   68.63
_cell_angle_beta   75.87
_cell_angle_gamma   70.47
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2Si
_chemical_formula_sum   'Na4 Si2'
_cell_volume   149.91
_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  Na0  1  0.0  0.31  0.09  1.0
  Na  Na1  1  0.0  0.55  0.19  1.0
  Na  Na2  1  0.0  0.89  0.67  1.0
  Na  Na3  1  0.0  0.98  0.05  1.0
  Si  Si4  1  0.0  0.49  0.6  1.0
  Si  Si5  1  0.0  0.63  0.33  1.0

Na Na Na Na Si Si
Na Na Na Na Si Si 0 2 o o o 0 1 o o o 1 5 o o o 1 2 + o o 2 5 - o o 3 4 o o o 4 5 - o o 