data_[Mg2Be2Se4]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Mg  1.3100  1.5000  0.8600
  Be  1.5700  1.0500  0.5900
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [Imm2]
_cell_length_a [3.3900]
_cell_length_b [3.5738]
_cell_length_c [12.3166]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [44]
_chemical_formula_structural [MgBeSe2]
_chemical_formula_sum '[Mg2 Be2 Se4]'
_cell_volume [149.2175]
_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
[
  Mg  Mg0  2  0.0000  0.5000  0.2039  1
  Be  Be1  2  0.0000  0.0000  0.4484  1
  Se  Se2  2  0.0000  0.0000  0.0379  1
  Se  Se3  2  0.0000  0.5000  0.8099  1
]