data_LiTlAs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.97
_cell_length_b   4.97
_cell_length_c   4.97
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   LiTlAs2
_chemical_formula_sum   'Li1 Tl1 As2'
_cell_volume   86.91
_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
  Li  Li2  1  0.0  0.0  0.0  1.0
  Tl  Tl3  1  0.52  0.52  0.52  1.0
  As  As0  1  0.76  0.76  0.76  1.0
  As  As1  1  0.27  0.27  0.27  1.0

data_LiTlAs2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.97
_cell_length_b   4.97
_cell_length_c   12.18
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   LiTlAs2
_chemical_formula_sum   'Li3 Tl3 As6'
_cell_volume   260.73
_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
  Li  Li0  3  0.0  0.0  0.0  1.0
  Tl  Tl1  3  0.0  0.0  0.48  1.0
  As  As2  3  0.0  0.0  0.24  1.0
  As  As3  3  0.0  0.0  0.73  1.0

Li Tl As As
LiTlAs2 is Heusler structured and crystallizes in the trigonal R3m space group. Li(1) is bonded in a 7-coordinate geometry to three equivalent As(2) and four equivalent As(1) atoms. All Li(1)-As(2) bond lengths are 2.96 Å. There is one shorter (2.95 Å) and three longer (3.08 Å) Li(1)-As(1) bond lengths. Tl(1) is bonded in a distorted body-centered cubic geometry to four equivalent As(1) and four equivalent As(2) atoms. There is one shorter (2.95 Å) and three longer (3.08 Å) Tl(1)-As(1) bond lengths. There is one shorter (2.95 Å) and three longer (3.08 Å) Tl(1)-As(2) bond lengths. There are two inequivalent As sites. In the first As site, As(1) is bonded in a body-centered cubic geometry to four equivalent Li(1) and four equivalent Tl(1) atoms. In the second As site, As(2) is bonded in a 7-coordinate geometry to three equivalent Li(1) and four equivalent Tl(1) atoms.