data_Na2VSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.76
_cell_length_b   3.76
_cell_length_c   5.06
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2VSi
_chemical_formula_sum   'Na2 V1 Si1'
_cell_volume   71.51
_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  0.88  0.0  0.53  1.0
  Na  Na1  1  0.0  0.88  0.53  1.0
  V  V3  1  0.88  0.88  0.0  1.0
  Si  Si2  1  0.0  0.0  0.0  1.0

data_Na2VSi
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.31
_cell_length_b   5.31
_cell_length_c   5.06
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Na2VSi
_chemical_formula_sum   'Na4 V2 Si2'
_cell_volume   143.01
_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+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
  Na  Na0  4  0.44  0.44  0.53  1.0
  V  V1  2  0.38  0.5  -0.0  1.0
  Si  Si2  2  0.0  0.0  0.0  1.0

Na Na V Si
Na Na V Si 0 1 + - o 2 3 + + o 