data_Rb2CaMg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.79
_cell_length_b   6.79
_cell_length_c   6.79
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Rb2CaMg
_chemical_formula_sum   'Rb2 Ca1 Mg1'
_cell_volume   221.13
_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
  Rb  Rb2  1  0.2  0.2  0.2  1.0
  Rb  Rb3  1  0.4  0.4  0.4  1.0
  Ca  Ca0  1  0.8  0.8  0.8  1.0
  Mg  Mg1  1  0.0  0.0  0.0  1.0

data_Rb2CaMg
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.79
_cell_length_b   6.79
_cell_length_c   16.63
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Rb2CaMg
_chemical_formula_sum   'Rb6 Ca3 Mg3'
_cell_volume   663.4
_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
  Rb  Rb0  3  0.0  0.0  0.6  1.0
  Rb  Rb1  3  0.0  0.0  0.8  1.0
  Ca  Ca2  3  0.0  0.0  0.2  1.0
  Mg  Mg3  3  0.0  0.0  -0.0  1.0

Rb Rb Ca Mg
Rb2CaMg crystallizes in the trigonal R3m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a distorted single-bond geometry to one Rb(2), three equivalent Ca(1), and one Mg(1) atom. The Rb(1)-Rb(2) bond length is 3.33 Å. All Rb(1)-Ca(1) bond lengths are 4.07 Å. The Rb(1)-Mg(1) bond length is 3.32 Å. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one Rb(1), three equivalent Ca(1), and three equivalent Mg(1) atoms. All Rb(2)-Ca(1) bond lengths are 4.07 Å. All Rb(2)-Mg(1) bond lengths are 4.07 Å. Ca(1) is bonded in a 7-coordinate geometry to three equivalent Rb(1), three equivalent Rb(2), and one Mg(1) atom. The Ca(1)-Mg(1) bond length is 3.33 Å. Mg(1) is bonded in a 5-coordinate geometry to one Rb(1), three equivalent Rb(2), and one Ca(1) atom.