data_CaCu2As
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.3
_cell_length_b   3.3
_cell_length_c   6.55
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaCu2As
_chemical_formula_sum   'Ca1 Cu2 As1'
_cell_volume   71.5
_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  0.95  1.0
  Cu  Cu2  1  0.65  0.65  0.42  1.0
  Cu  Cu3  1  0.0  0.0  0.57  1.0
  As  As0  1  0.65  0.65  0.88  1.0

data_CaCu2As
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.67
_cell_length_b   4.67
_cell_length_c   6.55
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   CaCu2As
_chemical_formula_sum   'Ca2 Cu4 As2'
_cell_volume   143.01
_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
  Ca  Ca0  2  0.0  0.0  0.95  1.0
  Cu  Cu1  2  0.0  0.0  0.57  1.0
  Cu  Cu2  2  0.15  0.5  0.42  1.0
  As  As3  2  0.15  0.5  0.88  1.0

Ca Cu Cu As
Ca Cu Cu As 0 3 - - o 1 2 + + o 