data_ErSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.81
_cell_length_b   3.82
_cell_length_c   5.65
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   ErSi
_chemical_formula_sum   'Er4 Si4'
_cell_volume   168.46
_cell_formula_units_Z   4
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  0.31  0.95  0.18  1.0
  Er  Er1  1  0.4  0.95  0.64  1.0
  Er  Er2  1  0.5  0.86  0.47  1.0
  Er  Er3  1  0.41  0.86  0.01  1.0
  Si  Si4  1  0.2  0.95  0.92  1.0
  Si  Si5  1  0.3  0.95  0.56  1.0
  Si  Si6  1  0.61  0.86  0.74  1.0
  Si  Si7  1  0.51  0.86  0.09  1.0

data_ErSi
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.82
_cell_length_b   5.65
_cell_length_c   7.81
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   ErSi
_chemical_formula_sum   'Er4 Si4'
_cell_volume   168.46
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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  2  0.45  0.14  0.1  1.0
  Er  Er1  2  0.45  0.68  0.0  1.0
  Si  Si2  2  0.45  0.41  0.2  1.0
  Si  Si3  2  0.45  0.76  0.11  1.0

Er Er Er Er Si Si Si Si
ErSi crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one ErSi cluster. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 4-coordinate geometry to one Er(2), one Si(1), and two equivalent Si(2) atoms. The Er(1)-Er(2) bond length is 1.32 Å. The Er(1)-Si(1) bond length is 1.70 Å. There is one shorter (1.73 Å) and one longer (2.15 Å) Er(1)-Si(2) bond length. In the second Er site, Er(2) is bonded in a distorted single-bond geometry to one Er(1), one Si(1), and one Si(2) atom. The Er(2)-Si(1) bond length is 1.73 Å. The Er(2)-Si(2) bond length is 0.93 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 2-coordinate geometry to one Er(1) and one Er(2) atom. In the second Si site, Si(2) is bonded in a single-bond geometry to one Er(2) and two equivalent Er(1) atoms.