The material described by TaNb(Cu3Se4)2 is Sulvanite-derived structured and crystallizes in the cubic F-43m space group. Ta(1) is bonded to four equivalent Se(2) atoms to form distorted TaSe4 tetrahedra that share edges with six equivalent Cu(1)Se4 tetrahedra. Nb(1) is bonded to four equivalent Se(1) atoms to form distorted NbSe4 tetrahedra that share edges with six equivalent Cu(1)Se4 tetrahedra. Cu(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with eight equivalent Cu(1)Se4 tetrahedra,  an edgeedge with one Ta(1)Se4 tetrahedra, and  an edgeedge with one Nb(1)Se4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Nb(1) and three equivalent Cu(1) atoms to form SeNbCu3 tetrahedra that share corners with six equivalent Se(2)TaCu3 tetrahedra and edges with three equivalent Se(1)NbCu3 tetrahedra. In the second Se site, Se(2) is bonded to one Ta(1) and three equivalent Cu(1) atoms to form SeTaCu3 tetrahedra that share corners with six equivalent Se(1)NbCu3 tetrahedra and edges with three equivalent Se(2)TaCu3 tetrahedra. is represented by the CIF card [CIF]
data_TaNb(Cu3Se4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.050
_cell_length_b   8.050
_cell_length_c   8.050
_cell_angle_alpha   60.000
_cell_angle_beta   60.000
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   368.818
_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
  Ta  Ta0  1  0.500  0.500  0.500  1.0
  Nb  Nb1  1  0.000  0.000  0.000  1.0
  Cu  Cu2  1  0.750  0.250  0.250  1.0
  Cu  Cu3  1  0.250  0.750  0.750  1.0
  Cu  Cu4  1  0.750  0.250  0.750  1.0
  Cu  Cu5  1  0.250  0.750  0.250  1.0
  Cu  Cu6  1  0.250  0.250  0.750  1.0
  Cu  Cu7  1  0.750  0.750  0.250  1.0
  Se  Se8  1  0.875  0.875  0.376  1.0
  Se  Se9  1  0.375  0.375  0.875  1.0
  Se  Se10  1  0.875  0.875  0.875  1.0
  Se  Se11  1  0.375  0.375  0.375  1.0
  Se  Se12  1  0.376  0.875  0.875  1.0
  Se  Se13  1  0.875  0.375  0.375  1.0
  Se  Se14  1  0.875  0.376  0.875  1.0
  Se  Se15  1  0.375  0.875  0.375  1.0
[/CIF]
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The material described by TaNb(Cu3Se4)2 is Sulvanite-derived structured and crystallizes in the cubic F-43m space group. Ta(1) is bonded to four equivalent Se(2) atoms to form distorted TaSe4 tetrahedra that share edges with six equivalent Cu(1)Se4 tetrahedra. Nb(1) is bonded to four equivalent Se(1) atoms to form distorted NbSe4 tetrahedra that share edges with six equivalent Cu(1)Se4 tetrahedra. Cu(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with eight equivalent Cu(1)Se4 tetrahedra,  an edgeedge with one Ta(1)Se4 tetrahedra, and  an edgeedge with one Nb(1)Se4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Nb(1) and three equivalent Cu(1) atoms to form SeNbCu3 tetrahedra that share corners with six equivalent Se(2)TaCu3 tetrahedra and edges with three equivalent Se(1)NbCu3 tetrahedra. In the second Se site, Se(2) is bonded to one Ta(1) and three equivalent Cu(1) atoms to form SeTaCu3 tetrahedra that share corners with six equivalent Se(1)NbCu3 tetrahedra and edges with three equivalent Se(2)TaCu3 tetrahedra. is represented by the CIF card [CIF]
data_TaNb(Cu3Se4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.050
_cell_length_b   8.050
_cell_length_c   8.050
_cell_angle_alpha   60.000
_cell_angle_beta   60.000
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   368.818
_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
  Ta  Ta0  1  0.500  0.500  0.500  1.0
  Nb  Nb1  1  0.000  0.000  0.000  1.0
  Cu  Cu2  1  0.750  0.250  0.250  1.0
  Cu  Cu3  1  0.250  0.750  0.750  1.0
  Cu  Cu4  1  0.750  0.250  0.750  1.0
  Cu  Cu5  1  0.250  0.750  0.250  1.0
  Cu  Cu6  1  0.250  0.250  0.750  1.0
  Cu  Cu7  1  0.750  0.750  0.250  1.0
  Se  Se8  1  0.875  0.875  0.376  1.0
  Se  Se9  1  0.375  0.375  0.875  1.0
  Se  Se10  1  0.875  0.875  0.875  1.0
  Se  Se11  1  0.375  0.375  0.375  1.0
  Se  Se12  1  0.376  0.875  0.875  1.0
  Se  Se13  1  0.875  0.375  0.375  1.0
  Se  Se14  1  0.875  0.376  0.875  1.0
  Se  Se15  1  0.375  0.875  0.375  1.0
[/CIF]
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