data_MgCuSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.81
_cell_length_b   4.81
_cell_length_c   5.33
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgCuSe
_chemical_formula_sum   'Mg2 Cu2 Se2'
_cell_volume   106.98
_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  Mg2  1  0.41  0.39  0.0  1.0
  Mg  Mg3  1  0.0  0.78  0.33  1.0
  Cu  Cu0  1  0.0  0.0  0.0  1.0
  Cu  Cu1  1  0.0  0.0  0.67  1.0
  Se  Se4  1  0.41  0.39  0.33  1.0
  Se  Se5  1  0.0  0.78  0.0  1.0

data_MgCuSe
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.81
_cell_length_b   4.81
_cell_length_c   5.33
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgCuSe
_chemical_formula_sum   'Mg2 Cu2 Se2'
_cell_volume   106.98
_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  1  -0.0  0.78  0.33  1.0
  Mg  Mg1  1  0.41  0.39  0.0  1.0
  Cu  Cu2  1  0.0  0.0  0.0  1.0
  Cu  Cu3  1  0.0  0.0  0.67  1.0
  Se  Se4  1  -0.0  0.78  0.0  1.0
  Se  Se5  1  0.41  0.39  0.33  1.0

Mg Mg Cu Cu Se Se
MgCuSe crystallizes in the triclinic P1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Cu(1), one Cu(2), one Se(1), and one Se(2) atom. The Mg(1)-Cu(1) bond length is 1.91 Å. The Mg(1)-Cu(2) bond length is 2.61 Å. The Mg(1)-Se(1) bond length is 1.77 Å. The Mg(1)-Se(2) bond length is 2.51 Å. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Cu(1), one Cu(2), one Se(2), and three equivalent Se(1) atoms. The Mg(2)-Cu(1) bond length is 2.08 Å. The Mg(2)-Cu(2) bond length is 2.08 Å. The Mg(2)-Se(2) bond length is 1.77 Å. There are a spread of Mg(2)-Se(1) bond distances ranging from 2.51-3.31 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Cu(2), and one Se(2) atom. The Cu(1)-Cu(2) bond length is 1.77 Å. The Cu(1)-Se(2) bond length is 1.07 Å. In the second Cu site, Cu(2) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Cu(1), one Se(1), and one Se(2) atom. The Cu(2)-Se(1) bond length is 2.61 Å. The Cu(2)-Se(2) bond length is 2.08 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 1-coordinate geometry to one Mg(1), three equivalent Mg(2), and one Cu(2) atom. In the second Se site, Se(2) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Cu(1), and one Cu(2) atom.