The crystal structure described by HfCrSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 8-coordinate geometry to one Cr(2), one Si(4), one Si(5), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. In the second Hf site, Hf(2) is bonded to two equivalent Cr(2), two equivalent Si(1), two equivalent Si(2), and three equivalent Si(4) atoms to form distorted HfCr2Si7 pentagonal bipyramids that share corners with two equivalent Cr(2)Hf4Cr2Si6 cuboctahedra, corners with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids, edges with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids, faces with two equivalent Cr(2)Hf4Cr2Si6 cuboctahedra, and  a faceface with one Hf(2)Cr2Si7 pentagonal bipyramid. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 6-coordinate geometry to one Cr(2), one Si(2), one Si(3), one Si(4), one Si(5), and two equivalent Si(1) atoms. In the second Cr site, Cr(2) is bonded to two equivalent Hf(1), two equivalent Hf(2), two equivalent Cr(1), two equivalent Si(1), two equivalent Si(4), and two equivalent Si(5) atoms to form distorted CrHf4Cr2Si6 cuboctahedra that share corners with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids,  an edgeedge with one Cr(2)Hf4Cr2Si6 cuboctahedra,  a faceface with one Cr(2)Hf4Cr2Si6 cuboctahedra, and faces with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids. There are five inequivalent Si sites. In the first Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Hf(2), four equivalent Hf(1), two equivalent Cr(1), and one Si(2) atom. In the second Si site, Si(3) is bonded in a 7-coordinate geometry to four equivalent Hf(1), two equivalent Cr(1), and one Si(3) atom. In the third Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Hf(1), three equivalent Hf(2), two equivalent Cr(1), and two equivalent Cr(2) atoms. In the fourth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Hf(1), two equivalent Cr(1), and two equivalent Cr(2) atoms. In the fifth Si site, Si(1) is bonded in a 7-coordinate geometry to one Hf(2), two equivalent Hf(1), one Cr(2), two equivalent Cr(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_HfCrSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.996
_cell_length_b   9.055
_cell_length_c   9.725
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   704.111
_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
  Hf  Hf0  1  0.746  0.828  0.048  1.0
  Hf  Hf1  1  0.746  0.172  0.952  1.0
  Hf  Hf2  1  0.254  0.672  0.548  1.0
  Hf  Hf3  1  0.254  0.328  0.452  1.0
  Hf  Hf4  1  0.254  0.172  0.952  1.0
  Hf  Hf5  1  0.254  0.828  0.048  1.0
  Hf  Hf6  1  0.746  0.328  0.452  1.0
  Hf  Hf7  1  0.746  0.672  0.548  1.0
  Hf  Hf8  1  0.500  0.831  0.320  1.0
  Hf  Hf9  1  0.500  0.169  0.680  1.0
  Hf  Hf10  1  0.500  0.669  0.820  1.0
  Hf  Hf11  1  0.500  0.331  0.180  1.0
  Cr  Cr12  1  0.749  0.579  0.248  1.0
  Cr  Cr13  1  0.749  0.421  0.752  1.0
  Cr  Cr14  1  0.251  0.921  0.748  1.0
  Cr  Cr15  1  0.251  0.079  0.252  1.0
  Cr  Cr16  1  0.251  0.421  0.752  1.0
  Cr  Cr17  1  0.251  0.579  0.248  1.0
  Cr  Cr18  1  0.749  0.079  0.252  1.0
  Cr  Cr19  1  0.749  0.921  0.748  1.0
  Cr  Cr20  1  0.744  0.000  0.500  1.0
  Cr  Cr21  1  0.256  0.500  0.000  1.0
  Cr  Cr22  1  0.256  0.000  0.500  1.0
  Cr  Cr23  1  0.744  0.500  0.000  1.0
  Si  Si24  1  0.851  0.829  0.319  1.0
  Si  Si25  1  0.851  0.171  0.681  1.0
  Si  Si26  1  0.149  0.671  0.819  1.0
  Si  Si27  1  0.149  0.329  0.181  1.0
  Si  Si28  1  0.149  0.171  0.681  1.0
  Si  Si29  1  0.149  0.829  0.319  1.0
  Si  Si30  1  0.851  0.329  0.181  1.0
  Si  Si31  1  0.851  0.671  0.819  1.0
  Si  Si32  1  0.500  0.539  0.380  1.0
  Si  Si33  1  0.500  0.461  0.620  1.0
  Si  Si34  1  0.500  0.961  0.880  1.0
  Si  Si35  1  0.500  0.039  0.120  1.0
  Si  Si36  1  0.000  0.540  0.376  1.0
  Si  Si37  1  0.000  0.460  0.624  1.0
  Si  Si38  1  0.000  0.960  0.876  1.0
  Si  Si39  1  0.000  0.040  0.124  1.0
  Si  Si40  1  0.500  0.627  0.104  1.0
  Si  Si41  1  0.500  0.373  0.896  1.0
  Si  Si42  1  0.500  0.873  0.604  1.0
  Si  Si43  1  0.500  0.127  0.396  1.0
  Si  Si44  1  0.000  0.614  0.098  1.0
  Si  Si45  1  0.000  0.386  0.902  1.0
  Si  Si46  1  0.000  0.886  0.598  1.0
  Si  Si47  1  0.000  0.114  0.402  1.0
[/CIF]
.
The crystal structure described by HfCrSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 8-coordinate geometry to one Cr(2), one Si(4), one Si(5), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. In the second Hf site, Hf(2) is bonded to two equivalent Cr(2), two equivalent Si(1), two equivalent Si(2), and three equivalent Si(4) atoms to form distorted HfCr2Si7 pentagonal bipyramids that share corners with two equivalent Cr(2)Hf4Cr2Si6 cuboctahedra, corners with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids, edges with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids, faces with two equivalent Cr(2)Hf4Cr2Si6 cuboctahedra, and  a faceface with one Hf(2)Cr2Si7 pentagonal bipyramid. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 6-coordinate geometry to one Cr(2), one Si(2), one Si(3), one Si(4), one Si(5), and two equivalent Si(1) atoms. In the second Cr site, Cr(2) is bonded to two equivalent Hf(1), two equivalent Hf(2), two equivalent Cr(1), two equivalent Si(1), two equivalent Si(4), and two equivalent Si(5) atoms to form distorted CrHf4Cr2Si6 cuboctahedra that share corners with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids,  an edgeedge with one Cr(2)Hf4Cr2Si6 cuboctahedra,  a faceface with one Cr(2)Hf4Cr2Si6 cuboctahedra, and faces with two equivalent Hf(2)Cr2Si7 pentagonal bipyramids. There are five inequivalent Si sites. In the first Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Hf(2), four equivalent Hf(1), two equivalent Cr(1), and one Si(2) atom. In the second Si site, Si(3) is bonded in a 7-coordinate geometry to four equivalent Hf(1), two equivalent Cr(1), and one Si(3) atom. In the third Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Hf(1), three equivalent Hf(2), two equivalent Cr(1), and two equivalent Cr(2) atoms. In the fourth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Hf(1), two equivalent Cr(1), and two equivalent Cr(2) atoms. In the fifth Si site, Si(1) is bonded in a 7-coordinate geometry to one Hf(2), two equivalent Hf(1), one Cr(2), two equivalent Cr(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_HfCrSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.996
_cell_length_b   9.055
_cell_length_c   9.725
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   704.111
_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
  Hf  Hf0  1  0.746  0.828  0.048  1.0
  Hf  Hf1  1  0.746  0.172  0.952  1.0
  Hf  Hf2  1  0.254  0.672  0.548  1.0
  Hf  Hf3  1  0.254  0.328  0.452  1.0
  Hf  Hf4  1  0.254  0.172  0.952  1.0
  Hf  Hf5  1  0.254  0.828  0.048  1.0
  Hf  Hf6  1  0.746  0.328  0.452  1.0
  Hf  Hf7  1  0.746  0.672  0.548  1.0
  Hf  Hf8  1  0.500  0.831  0.320  1.0
  Hf  Hf9  1  0.500  0.169  0.680  1.0
  Hf  Hf10  1  0.500  0.669  0.820  1.0
  Hf  Hf11  1  0.500  0.331  0.180  1.0
  Cr  Cr12  1  0.749  0.579  0.248  1.0
  Cr  Cr13  1  0.749  0.421  0.752  1.0
  Cr  Cr14  1  0.251  0.921  0.748  1.0
  Cr  Cr15  1  0.251  0.079  0.252  1.0
  Cr  Cr16  1  0.251  0.421  0.752  1.0
  Cr  Cr17  1  0.251  0.579  0.248  1.0
  Cr  Cr18  1  0.749  0.079  0.252  1.0
  Cr  Cr19  1  0.749  0.921  0.748  1.0
  Cr  Cr20  1  0.744  0.000  0.500  1.0
  Cr  Cr21  1  0.256  0.500  0.000  1.0
  Cr  Cr22  1  0.256  0.000  0.500  1.0
  Cr  Cr23  1  0.744  0.500  0.000  1.0
  Si  Si24  1  0.851  0.829  0.319  1.0
  Si  Si25  1  0.851  0.171  0.681  1.0
  Si  Si26  1  0.149  0.671  0.819  1.0
  Si  Si27  1  0.149  0.329  0.181  1.0
  Si  Si28  1  0.149  0.171  0.681  1.0
  Si  Si29  1  0.149  0.829  0.319  1.0
  Si  Si30  1  0.851  0.329  0.181  1.0
  Si  Si31  1  0.851  0.671  0.819  1.0
  Si  Si32  1  0.500  0.539  0.380  1.0
  Si  Si33  1  0.500  0.461  0.620  1.0
  Si  Si34  1  0.500  0.961  0.880  1.0
  Si  Si35  1  0.500  0.039  0.120  1.0
  Si  Si36  1  0.000  0.540  0.376  1.0
  Si  Si37  1  0.000  0.460  0.624  1.0
  Si  Si38  1  0.000  0.960  0.876  1.0
  Si  Si39  1  0.000  0.040  0.124  1.0
  Si  Si40  1  0.500  0.627  0.104  1.0
  Si  Si41  1  0.500  0.373  0.896  1.0
  Si  Si42  1  0.500  0.873  0.604  1.0
  Si  Si43  1  0.500  0.127  0.396  1.0
  Si  Si44  1  0.000  0.614  0.098  1.0
  Si  Si45  1  0.000  0.386  0.902  1.0
  Si  Si46  1  0.000  0.886  0.598  1.0
  Si  Si47  1  0.000  0.114  0.402  1.0
[/CIF]
.