data_Ge2AsSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.39
_cell_length_b   3.39
_cell_length_c   6.85
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ge2AsSe
_chemical_formula_sum   'Ge2 As1 Se1'
_cell_volume   78.82
_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
  Ge  Ge1  1  0.7  0.7  0.71  1.0
  Ge  Ge2  1  0.7  0.7  0.14  1.0
  As  As0  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.0  0.0  0.42  1.0

data_Ge2AsSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.8
_cell_length_b   4.8
_cell_length_c   6.85
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ge2AsSe
_chemical_formula_sum   'Ge4 As2 Se2'
_cell_volume   157.64
_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
  Ge  Ge0  2  0.2  0.5  0.14  1.0
  Ge  Ge1  2  0.2  0.5  0.71  1.0
  As  As2  2  0.0  0.0  0.0  1.0
  Se  Se3  2  0.0  0.0  0.42  1.0

Ge Ge As Se
Ge Ge As Se 0 3 + + o 0 2 + + + 1 2 + + o 1 3 + + o 2 3 o o o 
Ge2AsSe crystallizes in the monoclinic Cm space group. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a water-like geometry to one As(1) and one Se(1) atom. The Ge(1)-As(1) bond length is 2.49 Å. The Ge(1)-Se(1) bond length is 2.42 Å. In the second Ge site, Ge(2) is bonded in a 4-coordinate geometry to three equivalent As(1) and one Se(1) atom. There is one shorter (1.75 Å) and two longer (2.75 Å) Ge(2)-As(1) bond lengths. The Ge(2)-Se(1) bond length is 2.42 Å. As(1) is bonded in a distorted single-bond geometry to one Ge(1) and three equivalent Ge(2) atoms. Se(1) is bonded in a water-like geometry to one Ge(1) and one Ge(2) atom.