data_CaAsSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.56
_cell_length_b   3.56
_cell_length_c   6.99
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaAsSe2
_chemical_formula_sum   'Ca1 As1 Se2'
_cell_volume   88.53
_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  Ca1  1  0.0  0.0  0.0  1.0
  As  As0  1  0.0  0.0  0.5  1.0
  Se  Se2  1  0.78  0.78  0.77  1.0
  Se  Se3  1  0.78  0.78  0.23  1.0

data_CaAsSe2
_symmetry_space_group_name_H-M   Amm2
_cell_length_a   6.99
_cell_length_b   5.03
_cell_length_c   5.03
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   38
_chemical_formula_structural   CaAsSe2
_chemical_formula_sum   'Ca2 As2 Se4'
_cell_volume   177.06
_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, y, z'
  4  'x, -y, z'
  5  'x, y+1/2, z+1/2'
  6  '-x, -y+1/2, z+1/2'
  7  '-x, y+1/2, z+1/2'
  8  'x, -y+1/2, z+1/2'
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  2  0.0  0.0  0.0  1.0
  As  As1  2  0.5  0.0  0.0  1.0
  Se  Se2  4  0.23  0.0  0.78  1.0

Ca As Se Se
Ca As Se Se 0 2 - - - 0 3 - - o 1 3 - - o 1 2 - - o 