The crystal structure described by TiFeSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent Fe(2), four equivalent Fe(1), two equivalent Si(2), two equivalent Si(5), and three equivalent Si(3) atoms to form distorted TiFe6Si7 pentagonal bipyramids that share corners with two equivalent Ti(1)Fe6Si7 pentagonal bipyramids, edges with two equivalent Fe(2)Ti4Fe2Si6 cuboctahedra, faces with two equivalent Fe(2)Ti4Fe2Si6 cuboctahedra, and faces with three equivalent Ti(1)Fe6Si7 pentagonal bipyramids. In the second Ti site, Ti(2) is bonded in a 8-coordinate geometry to one Fe(2), three equivalent Fe(1), one Si(3), one Si(4), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(5) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to two equivalent Ti(1), three equivalent Ti(2), one Fe(2), one Si(1), one Si(2), one Si(3), one Si(4), and two equivalent Si(5) atoms. In the second Fe site, Fe(2) is bonded to two equivalent Ti(1), two equivalent Ti(2), two equivalent Fe(1), two equivalent Si(3), two equivalent Si(4), and two equivalent Si(5) atoms to form distorted FeTi4Fe2Si6 cuboctahedra that share  an edgeedge with one Fe(2)Ti4Fe2Si6 cuboctahedra, edges with two equivalent Ti(1)Fe6Si7 pentagonal bipyramids,  a faceface with one Fe(2)Ti4Fe2Si6 cuboctahedra, and faces with two equivalent Ti(1)Fe6Si7 pentagonal bipyramids. There are five inequivalent Si sites. In the first Si site, Si(4) is bonded in a 6-coordinate geometry to two equivalent Ti(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the second Si site, Si(5) is bonded in a 7-coordinate geometry to one Ti(1), two equivalent Ti(2), one Fe(2), two equivalent Fe(1), and one Si(5) atom. In the third Si site, Si(1) is bonded in a 7-coordinate geometry to four equivalent Ti(2), two equivalent Fe(1), and one Si(1) atom. In the fourth Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ti(1), four equivalent Ti(2), two equivalent Fe(1), and one Si(2) atom. In the fifth Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Ti(2), three equivalent Ti(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_TiFeSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.633
_cell_length_b   8.566
_cell_length_c   9.366
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   612.426
_cell_formula_units_Z   12
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
  Ti  Ti0  1  1.000  0.170  0.820  1.0
  Ti  Ti1  1  0.238  0.170  0.545  1.0
  Ti  Ti2  1  0.762  0.330  0.045  1.0
  Ti  Ti3  1  0.762  0.670  0.955  1.0
  Ti  Ti4  1  0.762  0.170  0.545  1.0
  Ti  Ti5  1  0.762  0.830  0.455  1.0
  Ti  Ti6  1  0.238  0.670  0.955  1.0
  Ti  Ti7  1  0.238  0.330  0.045  1.0
  Ti  Ti8  1  0.000  0.330  0.320  1.0
  Ti  Ti9  1  0.000  0.670  0.680  1.0
  Ti  Ti10  1  0.000  0.830  0.180  1.0
  Ti  Ti11  1  0.238  0.830  0.455  1.0
  Fe  Fe12  1  0.249  0.087  0.250  1.0
  Fe  Fe13  1  0.249  0.587  0.250  1.0
  Fe  Fe14  1  0.249  0.413  0.750  1.0
  Fe  Fe15  1  0.751  0.087  0.250  1.0
  Fe  Fe16  1  0.751  0.913  0.750  1.0
  Fe  Fe17  1  0.751  0.413  0.750  1.0
  Fe  Fe18  1  0.751  0.587  0.250  1.0
  Fe  Fe19  1  0.249  0.913  0.750  1.0
  Fe  Fe20  1  0.246  0.000  0.000  1.0
  Fe  Fe21  1  0.754  0.500  0.500  1.0
  Fe  Fe22  1  0.754  0.000  1.000  1.0
  Fe  Fe23  1  0.246  0.500  0.500  1.0
  Si  Si24  1  0.500  0.038  0.375  1.0
  Si  Si25  1  0.000  0.462  0.878  1.0
  Si  Si26  1  0.000  0.538  0.122  1.0
  Si  Si27  1  0.000  0.962  0.622  1.0
  Si  Si28  1  0.000  0.038  0.378  1.0
  Si  Si29  1  1.000  0.373  0.602  1.0
  Si  Si30  1  0.000  0.627  0.398  1.0
  Si  Si31  1  1.000  0.873  0.898  1.0
  Si  Si32  1  0.500  0.373  0.595  1.0
  Si  Si33  1  0.500  0.627  0.405  1.0
  Si  Si34  1  0.500  0.873  0.905  1.0
  Si  Si35  1  0.500  0.127  0.095  1.0
  Si  Si36  1  0.500  0.462  0.876  1.0
  Si  Si37  1  0.500  0.538  0.125  1.0
  Si  Si38  1  0.500  0.962  0.625  1.0
  Si  Si39  1  1.000  0.127  0.102  1.0
  Si  Si40  1  0.347  0.334  0.317  1.0
  Si  Si41  1  0.653  0.834  0.183  1.0
  Si  Si42  1  0.347  0.834  0.183  1.0
  Si  Si43  1  0.653  0.166  0.817  1.0
  Si  Si44  1  0.653  0.666  0.683  1.0
  Si  Si45  1  0.653  0.334  0.317  1.0
  Si  Si46  1  0.347  0.166  0.817  1.0
  Si  Si47  1  0.347  0.666  0.683  1.0
[/CIF]
.
The crystal structure described by TiFeSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent Fe(2), four equivalent Fe(1), two equivalent Si(2), two equivalent Si(5), and three equivalent Si(3) atoms to form distorted TiFe6Si7 pentagonal bipyramids that share corners with two equivalent Ti(1)Fe6Si7 pentagonal bipyramids, edges with two equivalent Fe(2)Ti4Fe2Si6 cuboctahedra, faces with two equivalent Fe(2)Ti4Fe2Si6 cuboctahedra, and faces with three equivalent Ti(1)Fe6Si7 pentagonal bipyramids. In the second Ti site, Ti(2) is bonded in a 8-coordinate geometry to one Fe(2), three equivalent Fe(1), one Si(3), one Si(4), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(5) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to two equivalent Ti(1), three equivalent Ti(2), one Fe(2), one Si(1), one Si(2), one Si(3), one Si(4), and two equivalent Si(5) atoms. In the second Fe site, Fe(2) is bonded to two equivalent Ti(1), two equivalent Ti(2), two equivalent Fe(1), two equivalent Si(3), two equivalent Si(4), and two equivalent Si(5) atoms to form distorted FeTi4Fe2Si6 cuboctahedra that share  an edgeedge with one Fe(2)Ti4Fe2Si6 cuboctahedra, edges with two equivalent Ti(1)Fe6Si7 pentagonal bipyramids,  a faceface with one Fe(2)Ti4Fe2Si6 cuboctahedra, and faces with two equivalent Ti(1)Fe6Si7 pentagonal bipyramids. There are five inequivalent Si sites. In the first Si site, Si(4) is bonded in a 6-coordinate geometry to two equivalent Ti(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the second Si site, Si(5) is bonded in a 7-coordinate geometry to one Ti(1), two equivalent Ti(2), one Fe(2), two equivalent Fe(1), and one Si(5) atom. In the third Si site, Si(1) is bonded in a 7-coordinate geometry to four equivalent Ti(2), two equivalent Fe(1), and one Si(1) atom. In the fourth Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ti(1), four equivalent Ti(2), two equivalent Fe(1), and one Si(2) atom. In the fifth Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Ti(2), three equivalent Ti(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_TiFeSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.633
_cell_length_b   8.566
_cell_length_c   9.366
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   612.426
_cell_formula_units_Z   12
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
  Ti  Ti0  1  1.000  0.170  0.820  1.0
  Ti  Ti1  1  0.238  0.170  0.545  1.0
  Ti  Ti2  1  0.762  0.330  0.045  1.0
  Ti  Ti3  1  0.762  0.670  0.955  1.0
  Ti  Ti4  1  0.762  0.170  0.545  1.0
  Ti  Ti5  1  0.762  0.830  0.455  1.0
  Ti  Ti6  1  0.238  0.670  0.955  1.0
  Ti  Ti7  1  0.238  0.330  0.045  1.0
  Ti  Ti8  1  0.000  0.330  0.320  1.0
  Ti  Ti9  1  0.000  0.670  0.680  1.0
  Ti  Ti10  1  0.000  0.830  0.180  1.0
  Ti  Ti11  1  0.238  0.830  0.455  1.0
  Fe  Fe12  1  0.249  0.087  0.250  1.0
  Fe  Fe13  1  0.249  0.587  0.250  1.0
  Fe  Fe14  1  0.249  0.413  0.750  1.0
  Fe  Fe15  1  0.751  0.087  0.250  1.0
  Fe  Fe16  1  0.751  0.913  0.750  1.0
  Fe  Fe17  1  0.751  0.413  0.750  1.0
  Fe  Fe18  1  0.751  0.587  0.250  1.0
  Fe  Fe19  1  0.249  0.913  0.750  1.0
  Fe  Fe20  1  0.246  0.000  0.000  1.0
  Fe  Fe21  1  0.754  0.500  0.500  1.0
  Fe  Fe22  1  0.754  0.000  1.000  1.0
  Fe  Fe23  1  0.246  0.500  0.500  1.0
  Si  Si24  1  0.500  0.038  0.375  1.0
  Si  Si25  1  0.000  0.462  0.878  1.0
  Si  Si26  1  0.000  0.538  0.122  1.0
  Si  Si27  1  0.000  0.962  0.622  1.0
  Si  Si28  1  0.000  0.038  0.378  1.0
  Si  Si29  1  1.000  0.373  0.602  1.0
  Si  Si30  1  0.000  0.627  0.398  1.0
  Si  Si31  1  1.000  0.873  0.898  1.0
  Si  Si32  1  0.500  0.373  0.595  1.0
  Si  Si33  1  0.500  0.627  0.405  1.0
  Si  Si34  1  0.500  0.873  0.905  1.0
  Si  Si35  1  0.500  0.127  0.095  1.0
  Si  Si36  1  0.500  0.462  0.876  1.0
  Si  Si37  1  0.500  0.538  0.125  1.0
  Si  Si38  1  0.500  0.962  0.625  1.0
  Si  Si39  1  1.000  0.127  0.102  1.0
  Si  Si40  1  0.347  0.334  0.317  1.0
  Si  Si41  1  0.653  0.834  0.183  1.0
  Si  Si42  1  0.347  0.834  0.183  1.0
  Si  Si43  1  0.653  0.166  0.817  1.0
  Si  Si44  1  0.653  0.666  0.683  1.0
  Si  Si45  1  0.653  0.334  0.317  1.0
  Si  Si46  1  0.347  0.166  0.817  1.0
  Si  Si47  1  0.347  0.666  0.683  1.0
[/CIF]
.