data_CaGe2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.05
_cell_length_b   5.05
_cell_length_c   5.05
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaGe2Se
_chemical_formula_sum   'Ca1 Ge2 Se1'
_cell_volume   90.82
_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
  Ca  Ca0  1  0.0  0.0  0.0  1.0
  Ge  Ge1  1  0.78  0.78  0.78  1.0
  Ge  Ge2  1  0.35  0.35  0.35  1.0
  Se  Se3  1  0.57  0.57  0.57  1.0

data_CaGe2Se
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.05
_cell_length_b   5.05
_cell_length_c   12.36
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   CaGe2Se
_chemical_formula_sum   'Ca3 Ge6 Se3'
_cell_volume   272.46
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Ca  Ca0  3  0.0  0.0  0.0  1.0
  Ge  Ge1  3  0.0  0.0  0.22  1.0
  Ge  Ge2  3  0.0  0.0  0.65  1.0
  Se  Se3  3  0.0  0.0  0.43  1.0

Ca Ge Ge Se
CaGe2Se is Heusler structured and crystallizes in the trigonal R3m space group. Ca(1) is bonded in a 10-coordinate geometry to three equivalent Ge(2), four equivalent Ge(1), and three equivalent Se(1) atoms. All Ca(1)-Ge(2) bond lengths are 2.92 Å. There is one shorter (2.67 Å) and three longer (3.25 Å) Ca(1)-Ge(1) bond lengths. All Ca(1)-Se(1) bond lengths are 3.16 Å. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 5-coordinate geometry to four equivalent Ca(1) and one Se(1) atom. The Ge(1)-Se(1) bond length is 2.67 Å. In the second Ge site, Ge(2) is bonded to three equivalent Ca(1) and one Se(1) atom to form corner-sharing GeCa3Se trigonal pyramids. The Ge(2)-Se(1) bond length is 2.67 Å. Se(1) is bonded in a 5-coordinate geometry to three equivalent Ca(1), one Ge(1), and one Ge(2) atom.