The material described by MgSiO2(OH)2 is Pb(Zr_(1-x)Ti_x)O3-derived structured and crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with eight equivalent Si(1)O6 octahedra and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. Si(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form SiO6 octahedra that share corners with eight equivalent Mg(1)O6 octahedra and edges with two equivalent Si(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(1) and one O(3) atom. In the second H site, H(2) is bonded in a linear geometry to one O(2) and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1), one Si(1), and one H(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Si(1), and one H(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Mg(1), one Si(1), and one H(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Si(1), and one H(2) atom. is represented by the CIF file [CIF]
data_MgSi(HO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.860
_cell_length_b   4.335
_cell_length_c   4.801
_cell_angle_alpha   86.658
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   59.416
_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
  Mg  Mg0  1  0.500  0.500  0.525  1.0
  Si  Si1  1  0.000  0.001  0.998  1.0
  H  H2  1  0.000  0.979  0.483  1.0
  H  H3  1  0.500  0.465  0.029  1.0
  O  O4  1  0.000  0.224  0.691  1.0
  O  O5  1  0.500  0.248  0.141  1.0
  O  O6  1  0.000  0.803  0.341  1.0
  O  O7  1  0.500  0.772  0.894  1.0
[/CIF]
.
The material described by MgSiO2(OH)2 is Pb(Zr_(1-x)Ti_x)O3-derived structured and crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with eight equivalent Si(1)O6 octahedra and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. Si(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form SiO6 octahedra that share corners with eight equivalent Mg(1)O6 octahedra and edges with two equivalent Si(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(1) and one O(3) atom. In the second H site, H(2) is bonded in a linear geometry to one O(2) and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1), one Si(1), and one H(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Si(1), and one H(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Mg(1), one Si(1), and one H(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Si(1), and one H(2) atom. is represented by the CIF file [CIF]
data_MgSi(HO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.860
_cell_length_b   4.335
_cell_length_c   4.801
_cell_angle_alpha   86.658
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   59.416
_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
  Mg  Mg0  1  0.500  0.500  0.525  1.0
  Si  Si1  1  0.000  0.001  0.998  1.0
  H  H2  1  0.000  0.979  0.483  1.0
  H  H3  1  0.500  0.465  0.029  1.0
  O  O4  1  0.000  0.224  0.691  1.0
  O  O5  1  0.500  0.248  0.141  1.0
  O  O6  1  0.000  0.803  0.341  1.0
  O  O7  1  0.500  0.772  0.894  1.0
[/CIF]
.