data_As4Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.36
_cell_length_b   8.36
_cell_length_c   8.36
_cell_angle_alpha   109.47
_cell_angle_beta   109.47
_cell_angle_gamma   109.47
_symmetry_Int_Tables_number   1
_chemical_formula_structural   As4Se
_chemical_formula_sum   'As16 Se4'
_cell_volume   449.18
_cell_formula_units_Z   4
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
  As  As0  1  0.41  0.59  0.59  1.0
  As  As1  1  0.59  0.41  0.59  1.0
  As  As2  1  0.59  0.59  0.41  1.0
  As  As3  1  0.24  0.24  0.24  1.0
  As  As4  1  0.26  0.0  0.0  1.0
  As  As5  1  0.39  0.0  0.0  1.0
  As  As6  1  0.0  0.39  0.0  1.0
  As  As7  1  0.0  0.26  0.0  1.0
  As  As8  1  0.0  0.0  0.39  1.0
  As  As9  1  0.0  0.0  0.26  1.0
  As  As10  1  0.71  0.82  0.0  1.0
  As  As11  1  0.11  0.0  0.82  1.0
  As  As12  1  0.82  0.11  0.0  1.0
  As  As13  1  0.0  0.71  0.82  1.0
  As  As14  1  0.0  0.82  0.11  1.0
  As  As15  1  0.82  0.0  0.71  1.0
  Se  Se16  1  0.76  0.24  0.24  1.0
  Se  Se17  1  0.24  0.76  0.24  1.0
  Se  Se18  1  0.24  0.24  0.76  1.0
  Se  Se19  1  0.59  0.59  0.59  1.0

data_As4Se
_symmetry_space_group_name_H-M   R3
_cell_length_a   13.65
_cell_length_b   13.65
_cell_length_c   8.36
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   As4Se
_chemical_formula_sum   'As48 Se12'
_cell_volume   1347.53
_cell_formula_units_Z   12
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  'x+2/3, y+1/3, z+1/3'
  5  '-y+2/3, x-y+1/3, z+1/3'
  6  '-x+y+2/3, -x+1/3, z+1/3'
  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'
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
  As  As0  9  0.02  0.87  0.98  1.0
  As  As1  9  0.06  0.94  0.53  1.0
  As  As2  9  0.15  0.02  0.85  1.0
  As  As3  9  0.17  0.09  0.09  1.0
  As  As4  9  0.2  0.41  0.8  1.0
  As  As5  3  0.0  0.0  0.24  1.0
  Se  Se6  9  0.02  0.51  0.75  1.0
  Se  Se7  3  0.0  0.0  0.59  1.0

As As As As As As As As As As As As As As As As Se Se Se Se
As4Se crystallizes in the trigonal R3 space group. There are six inequivalent As sites. In the first As site, As(1) is bonded in a single-bond geometry to one As(2), one As(5), and one Se(2) atom. The As(1)-As(2) bond length is 2.80 Å. The As(1)-As(5) bond length is 2.91 Å. The As(1)-Se(2) bond length is 1.46 Å. In the second As site, As(2) is bonded in a 6-coordinate geometry to three equivalent As(1) and three equivalent As(3) atoms. All As(2)-As(3) bond lengths are 2.39 Å. In the third As site, As(3) is bonded in a distorted bent 120 degrees geometry to one As(2), one As(4), one As(5), and one As(6) atom. The As(3)-As(4) bond length is 1.13 Å. The As(3)-As(5) bond length is 2.16 Å. The As(3)-As(6) bond length is 1.56 Å. In the fourth As site, As(4) is bonded in a distorted bent 120 degrees geometry to one As(3) and one Se(1) atom. The As(4)-Se(1) bond length is 2.57 Å. In the fifth As site, As(5) is bonded in a 5-coordinate geometry to one As(1), one As(3), two equivalent As(6), and one Se(2) atom. Both As(5)-As(6) bond lengths are 2.28 Å. The As(5)-Se(2) bond length is 2.94 Å. In the sixth As site, As(6) is bonded in a 2-coordinate geometry to one As(3), two equivalent As(5), and one Se(1) atom. The As(6)-Se(1) bond length is 2.24 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in an L-shaped geometry to one As(4) and one As(6) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to three equivalent As(1) and three equivalent As(5) atoms.