data_CuSiAs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.55
_cell_length_b   4.55
_cell_length_c   4.55
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CuSiAs2
_chemical_formula_sum   'Cu1 Si1 As2'
_cell_volume   66.61
_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
  Cu  Cu2  1  0.61  0.61  0.61  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0
  As  As0  1  0.83  0.83  0.83  1.0
  As  As1  1  0.22  0.22  0.22  1.0

data_CuSiAs2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.55
_cell_length_b   4.55
_cell_length_c   11.15
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   CuSiAs2
_chemical_formula_sum   'Cu3 Si3 As6'
_cell_volume   199.83
_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
  Si  Si0  3  0.0  0.0  0.0  1.0
  Cu  Cu1  3  0.0  0.0  0.39  1.0
  As  As2  3  0.0  0.0  0.17  1.0
  As  As3  3  0.0  0.0  0.78  1.0

Cu Si As As
Cu Si As As 0 2 o - o 0 2 - o o 0 2 o o - 0 2 o o o 0 3 o o + 0 3 o + o 0 3 + o o 0 1 o + + 0 1 + o + 0 1 + + o 1 2 - - - 1 3 o o o 1 3 o o - 1 3 - o o 1 3 o - o 2 3 + + o 2 3 + o + 2 3 o + + 
CuSiAs2 crystallizes in the trigonal R3m space group. Cu(1) is bonded in a 10-coordinate geometry to three equivalent Si(1), three equivalent As(2), and four equivalent As(1) atoms. All Cu(1)-Si(1) bond lengths are 2.71 Å. All Cu(1)-As(2) bond lengths are 2.71 Å. There is one shorter (2.42 Å) and three longer (2.93 Å) Cu(1)-As(1) bond lengths. Si(1) is bonded in a distorted linear geometry to three equivalent Cu(1), one As(1), and four equivalent As(2) atoms. The Si(1)-As(1) bond length is 1.94 Å. There is one shorter (2.42 Å) and three longer (2.93 Å) Si(1)-As(2) bond lengths. There are two inequivalent As sites. In the first As site, As(1) is bonded in a distorted linear geometry to four equivalent Cu(1), one Si(1), and three equivalent As(2) atoms. All As(1)-As(2) bond lengths are 2.71 Å. In the second As site, As(2) is bonded in a 10-coordinate geometry to three equivalent Cu(1), four equivalent Si(1), and three equivalent As(1) atoms.