data_Ca2VSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.22
_cell_length_b   5.22
_cell_length_c   5.22
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca2VSe
_chemical_formula_sum   'Ca2 V1 Se1'
_cell_volume   100.6
_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  0.54  0.54  0.54  1.0
  Ca  Ca1  1  0.0  0.0  0.0  1.0
  V  V3  1  0.69  0.69  0.69  1.0
  Se  Se2  1  0.85  0.85  0.85  1.0

data_Ca2VSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.22
_cell_length_b   5.22
_cell_length_c   12.79
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Ca2VSe
_chemical_formula_sum   'Ca6 V3 Se3'
_cell_volume   301.8
_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
  Ca  Ca1  3  0.0  0.0  0.46  1.0
  V  V2  3  0.0  0.0  0.31  1.0
  Se  Se3  3  0.0  0.0  0.15  1.0

Ca Ca V Se
Ca2VSe crystallizes in the trigonal R3m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one V(1) and three equivalent Se(1) atoms to form distorted corner-sharing CaVSe3 trigonal pyramids. The Ca(1)-V(1) bond length is 1.97 Å. All Ca(1)-Se(1) bond lengths are 3.03 Å. In the second Ca site, Ca(2) is bonded in a single-bond geometry to one Se(1) atom. The Ca(2)-Se(1) bond length is 1.97 Å. V(1) is bonded in a distorted linear geometry to one Ca(1) and one Se(1) atom. The V(1)-Se(1) bond length is 1.97 Å. Se(1) is bonded in a distorted linear geometry to one Ca(2), three equivalent Ca(1), and one V(1) atom.