data_MgNb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.45
_cell_length_b   5.45
_cell_length_c   5.45
_cell_angle_alpha   31.12
_cell_angle_beta   31.12
_cell_angle_gamma   31.12
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgNb
_chemical_formula_sum   'Mg1 Nb1'
_cell_volume   38.35
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Nb  Nb1  1  0.0  0.0  0.77  1.0

data_MgNb
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.06
_cell_length_b   2.92
_cell_length_c   5.45
_cell_angle_alpha   90.0
_cell_angle_beta   108.04
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgNb
_chemical_formula_sum   'Mg2 Nb2'
_cell_volume   76.71
_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
  Mg  Mg0  2  0.0  0.0  0.0  1.0
  Nb  Nb1  2  0.0  0.0  0.23  1.0

Mg Nb
Mg Nb 0 1 o o - 