data_Na2CuSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.65
_cell_length_b   4.65
_cell_length_c   4.65
_cell_angle_alpha   119.37
_cell_angle_beta   119.37
_cell_angle_gamma   91.09
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2CuSi
_chemical_formula_sum   'Na2 Cu1 Si1'
_cell_volume   71.81
_cell_formula_units_Z   1
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  Na1  1  0.0  0.0  0.0  1.0
  Na  Na2  1  0.35  0.0  0.63  1.0
  Cu  Cu0  1  0.0  0.35  0.63  1.0
  Si  Si3  1  0.0  0.0  0.26  1.0

data_Na2CuSi
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.65
_cell_length_b   4.65
_cell_length_c   4.65
_cell_angle_alpha   91.09
_cell_angle_beta   119.37
_cell_angle_gamma   119.37
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2CuSi
_chemical_formula_sum   'Na2 Cu1 Si1'
_cell_volume   71.81
_cell_formula_units_Z   1
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  0.0  0.0  1.0
  Na  Na1  1  0.63  0.28  0.63  1.0
  Si  Si2  1  0.26  0.26  0.26  1.0
  Cu  Cu3  1  0.63  0.63  0.28  1.0

Na Na Cu Si
Na Na Cu Si 0 3 o o o 1 3 o o o 2 3 o o o 