data_Na2FeSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.85
_cell_length_b   4.95
_cell_length_c   5.08
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2FeSi
_chemical_formula_sum   'Na2 Fe1 Si1'
_cell_volume   71.68
_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  0.42  0.48  0.82  1.0
  Na  Na2  1  0.42  0.48  0.26  1.0
  Fe  Fe0  1  0.0  0.0  0.54  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0

data_Na2FeSi
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.85
_cell_length_b   4.95
_cell_length_c   5.08
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2FeSi
_chemical_formula_sum   'Na2 Fe1 Si1'
_cell_volume   71.68
_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  0.42  0.48  0.26  1.0
  Na  Na1  1  0.42  0.48  0.82  1.0
  Fe  Fe2  1  0.0  0.0  0.54  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0

Na Na Fe Si
Na Na Fe Si 0 2 o o o 0 2 o + o 0 2 + o o 0 3 o o + 0 3 o + + 0 3 + o + 0 3 + + + 0 0 + o o 0 1 o o o 0 1 o o + 1 3 o o o 1 3 o + o 1 3 + o o 1 2 o o o 1 2 o + o 1 2 + o o 1 1 + o o 2 2 + o o 2 3 o o o 2 3 o o + 3 3 + o o 
Na2FeSi is beta-derived structured and crystallizes in the triclinic P1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent Na(1), two equivalent Na(2), four equivalent Fe(1), and four equivalent Si(1) atoms to form distorted NaNa4Fe4Si4 cuboctahedra that share corners with four equivalent Na(1)Na4Fe4Si4 cuboctahedra, corners with eight equivalent Na(2)Na4Fe4Si4 cuboctahedra, edges with four equivalent Na(1)Na4Fe4Si4 cuboctahedra, edges with four equivalent Na(2)Na4Fe4Si4 cuboctahedra, edges with eight equivalent Fe(1)Na8Fe2Si2 cuboctahedra, edges with eight equivalent Si(1)Na8Fe2Si2 cuboctahedra, faces with four equivalent Na(1)Na4Fe4Si4 cuboctahedra, faces with four equivalent Fe(1)Na8Fe2Si2 cuboctahedra, faces with four equivalent Si(1)Na8Fe2Si2 cuboctahedra, and faces with six equivalent Na(2)Na4Fe4Si4 cuboctahedra. Both Na(1)-Na(1) bond lengths are 2.85 Å. There is one shorter (2.26 Å) and one longer (2.82 Å) Na(1)-Na(2) bond length. There are a spread of Na(1)-Fe(1) bond distances ranging from 3.01-3.38 Å. There are a spread of Na(1)-Si(1) bond distances ranging from 2.81-3.20 Å. In the second Na site, Na(2) is bonded to two equivalent Na(1), two equivalent Na(2), four equivalent Fe(1), and four equivalent Si(1) atoms to form distorted NaNa4Fe4Si4 cuboctahedra that share corners with four equivalent Na(2)Na4Fe4Si4 cuboctahedra, corners with eight equivalent Na(1)Na4Fe4Si4 cuboctahedra, edges with four equivalent Na(1)Na4Fe4Si4 cuboctahedra, edges with four equivalent Na(2)Na4Fe4Si4 cuboctahedra, edges with eight equivalent Fe(1)Na8Fe2Si2 cuboctahedra, edges with eight equivalent Si(1)Na8Fe2Si2 cuboctahedra, faces with four equivalent Na(2)Na4Fe4Si4 cuboctahedra, faces with four equivalent Fe(1)Na8Fe2Si2 cuboctahedra, faces with four equivalent Si(1)Na8Fe2Si2 cuboctahedra, and faces with six equivalent Na(1)Na4Fe4Si4 cuboctahedra. Both Na(2)-Na(2) bond lengths are 2.85 Å. There are a spread of Na(2)-Fe(1) bond distances ranging from 3.01-3.38 Å. There are a spread of Na(2)-Si(1) bond distances ranging from 2.98-3.35 Å. Fe(1) is bonded to four equivalent Na(1), four equivalent Na(2), two equivalent Fe(1), and two equivalent Si(1) atoms to form distorted FeNa8Fe2Si2 cuboctahedra that share corners with four equivalent Fe(1)Na8Fe2Si2 cuboctahedra, corners with eight equivalent Si(1)Na8Fe2Si2 cuboctahedra, edges with four equivalent Fe(1)Na8Fe2Si2 cuboctahedra, edges with four equivalent Si(1)Na8Fe2Si2 cuboctahedra, edges with eight equivalent Na(1)Na4Fe4Si4 cuboctahedra, edges with eight equivalent Na(2)Na4Fe4Si4 cuboctahedra, faces with four equivalent Na(1)Na4Fe4Si4 cuboctahedra, faces with four equivalent Na(2)Na4Fe4Si4 cuboctahedra, faces with four equivalent Fe(1)Na8Fe2Si2 cuboctahedra, and faces with six equivalent Si(1)Na8Fe2Si2 cuboctahedra. Both Fe(1)-Fe(1) bond lengths are 2.85 Å. There is one shorter (2.33 Å) and one longer (2.76 Å) Fe(1)-Si(1) bond length. Si(1) is bonded to four equivalent Na(1), four equivalent Na(2), two equivalent Fe(1), and two equivalent Si(1) atoms to form distorted SiNa8Fe2Si2 cuboctahedra that share corners with four equivalent Si(1)Na8Fe2Si2 cuboctahedra, corners with eight equivalent Fe(1)Na8Fe2Si2 cuboctahedra, edges with four equivalent Fe(1)Na8Fe2Si2 cuboctahedra, edges with four equivalent Si(1)Na8Fe2Si2 cuboctahedra, edges with eight equivalent Na(1)Na4Fe4Si4 cuboctahedra, edges with eight equivalent Na(2)Na4Fe4Si4 cuboctahedra, faces with four equivalent Na(1)Na4Fe4Si4 cuboctahedra, faces with four equivalent Na(2)Na4Fe4Si4 cuboctahedra, faces with four equivalent Si(1)Na8Fe2Si2 cuboctahedra, and faces with six equivalent Fe(1)Na8Fe2Si2 cuboctahedra. Both Si(1)-Si(1) bond lengths are 2.85 Å.