data_Er2MgBe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.05
_cell_length_b   5.05
_cell_length_c   5.05
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Er2MgBe
_chemical_formula_sum   'Er2 Mg1 Be1'
_cell_volume   90.97
_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  Er1  1  0.78  0.78  0.78  1.0
  Er  Er2  1  0.35  0.35  0.35  1.0
  Mg  Mg3  1  0.57  0.57  0.57  1.0
  Be  Be0  1  0.0  0.0  0.0  1.0

data_Er2MgBe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.05
_cell_length_b   5.05
_cell_length_c   12.37
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Er2MgBe
_chemical_formula_sum   'Er6 Mg3 Be3'
_cell_volume   272.91
_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  0.22  1.0
  Er  Er1  3  0.0  0.0  0.65  1.0
  Mg  Mg2  3  0.0  0.0  0.43  1.0
  Be  Be3  3  0.0  0.0  -0.0  1.0

Er Er Mg Be
MgBeEr2 is Heusler structured and crystallizes in the trigonal R3m space group. Mg(1) is bonded in a distorted linear geometry to one Er(1) and one Er(2) atom. The Mg(1)-Er(1) bond length is 2.66 Å. The Mg(1)-Er(2) bond length is 2.66 Å. Be(1) is bonded in a 4-coordinate geometry to one Er(1) and three equivalent Er(2) atoms. The Be(1)-Er(1) bond length is 2.66 Å. All Be(1)-Er(2) bond lengths are 2.93 Å. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 2-coordinate geometry to one Mg(1) and one Be(1) atom. In the second Er site, Er(2) is bonded to one Mg(1) and three equivalent Be(1) atoms to form distorted corner-sharing ErMgBe3 trigonal pyramids.