data_ErFeSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.47
_cell_length_b   4.47
_cell_length_c   4.47
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   ErFeSi2
_chemical_formula_sum   'Er1 Fe1 Si2'
_cell_volume   63.07
_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
  Er  Er0  1  0.16  0.16  0.16  1.0
  Fe  Fe1  1  0.0  0.0  0.0  1.0
  Si  Si2  1  0.58  0.58  0.58  1.0
  Si  Si3  1  0.74  0.74  0.74  1.0

data_ErFeSi2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.47
_cell_length_b   4.47
_cell_length_c   10.94
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   ErFeSi2
_chemical_formula_sum   'Er3 Fe3 Si6'
_cell_volume   189.22
_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
  Er  Er0  3  0.0  0.0  0.84  1.0
  Fe  Fe1  3  0.0  0.0  0.0  1.0
  Si  Si2  3  0.0  0.0  0.26  1.0
  Si  Si3  3  0.0  0.0  0.42  1.0

Er Fe Si Si
Er Fe Si Si 0 1 o o o 2 3 o o o 
ErFeSi2 crystallizes in the trigonal R3m space group. Er(1) is bonded in a distorted single-bond geometry to one Fe(1), three equivalent Si(1), and three equivalent Si(2) atoms. The Er(1)-Fe(1) bond length is 1.74 Å. All Er(1)-Si(1) bond lengths are 2.75 Å. All Er(1)-Si(2) bond lengths are 2.75 Å. Fe(1) is bonded in a single-bond geometry to one Er(1), three equivalent Si(1), and four equivalent Si(2) atoms. All Fe(1)-Si(1) bond lengths are 2.75 Å. There are three shorter (2.70 Å) and one longer (2.86 Å) Fe(1)-Si(2) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to three equivalent Er(1), three equivalent Fe(1), and one Si(2) atom to form distorted edge-sharing SiEr3Fe3Si tetrahedra. The Si(1)-Si(2) bond length is 1.74 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to three equivalent Er(1), four equivalent Fe(1), and one Si(1) atom.