data_[K2Mg2Fe2Se6]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  K  0.8200  2.2000  1.5200
  Mg  1.3100  1.5000  0.8600
  Fe  1.8300  1.4000  0.8525
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [P2_1/m]
_cell_length_a [8.7535]
_cell_length_b [3.9987]
_cell_length_c [9.7051]
_cell_angle_alpha [90.0000]
_cell_angle_beta [113.8338]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [11]
_chemical_formula_structural [KMgFeSe3]
_chemical_formula_sum '[K2 Mg2 Fe2 Se6]'
_cell_volume [310.7387]
_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
[
  K  K0  2  0.2278  0.7500  0.7449  1
  Mg  Mg1  2  0.3493  0.2500  0.3787  1
  Fe  Fe2  2  0.1002  0.7500  0.1127  1
  Se  Se3  2  0.1113  0.7500  0.3551  1
  Se  Se4  2  0.2004  0.2500  0.0311  1
  Se  Se5  2  0.4795  0.2500  0.6751  1
]