The compound described by Ca2SiO4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(3)O6 octahedra. In the third Ca site, Ca(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(2)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with three equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-62°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom to form distorted corner-sharing OCa3Si tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.393
_cell_length_b   6.977
_cell_length_c   9.905
_cell_angle_alpha   87.904
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   372.444
_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
  Ca  Ca0  1  0.002  0.792  0.158  1.0
  Ca  Ca1  1  0.998  0.208  0.842  1.0
  Ca  Ca2  1  0.000  0.500  0.500  1.0
  Ca  Ca3  1  0.000  0.000  0.500  1.0
  Ca  Ca4  1  0.502  0.208  0.342  1.0
  Ca  Ca5  1  0.498  0.792  0.658  1.0
  Ca  Ca6  1  0.500  0.500  0.000  1.0
  Ca  Ca7  1  0.500  0.000  0.000  1.0
  Si  Si8  1  0.000  0.279  0.172  1.0
  Si  Si9  1  1.000  0.721  0.828  1.0
  Si  Si10  1  0.500  0.279  0.672  1.0
  Si  Si11  1  0.500  0.721  0.328  1.0
  O  O12  1  0.952  0.239  0.337  1.0
  O  O13  1  0.048  0.761  0.663  1.0
  O  O14  1  0.119  0.512  0.872  1.0
  O  O15  1  0.149  0.890  0.908  1.0
  O  O16  1  0.298  0.248  0.132  1.0
  O  O17  1  0.351  0.890  0.408  1.0
  O  O18  1  0.202  0.248  0.632  1.0
  O  O19  1  0.381  0.512  0.372  1.0
  O  O20  1  0.452  0.761  0.163  1.0
  O  O21  1  0.548  0.239  0.837  1.0
  O  O22  1  0.619  0.488  0.628  1.0
  O  O23  1  0.798  0.752  0.368  1.0
  O  O24  1  0.649  0.110  0.592  1.0
  O  O25  1  0.702  0.752  0.868  1.0
  O  O26  1  0.851  0.110  0.092  1.0
  O  O27  1  0.881  0.488  0.128  1.0
[/CIF]
.
The compound described by Ca2SiO4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(3)O6 octahedra. In the third Ca site, Ca(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(2)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with three equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-62°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom to form distorted corner-sharing OCa3Si tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.393
_cell_length_b   6.977
_cell_length_c   9.905
_cell_angle_alpha   87.904
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   372.444
_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
  Ca  Ca0  1  0.002  0.792  0.158  1.0
  Ca  Ca1  1  0.998  0.208  0.842  1.0
  Ca  Ca2  1  0.000  0.500  0.500  1.0
  Ca  Ca3  1  0.000  0.000  0.500  1.0
  Ca  Ca4  1  0.502  0.208  0.342  1.0
  Ca  Ca5  1  0.498  0.792  0.658  1.0
  Ca  Ca6  1  0.500  0.500  0.000  1.0
  Ca  Ca7  1  0.500  0.000  0.000  1.0
  Si  Si8  1  0.000  0.279  0.172  1.0
  Si  Si9  1  1.000  0.721  0.828  1.0
  Si  Si10  1  0.500  0.279  0.672  1.0
  Si  Si11  1  0.500  0.721  0.328  1.0
  O  O12  1  0.952  0.239  0.337  1.0
  O  O13  1  0.048  0.761  0.663  1.0
  O  O14  1  0.119  0.512  0.872  1.0
  O  O15  1  0.149  0.890  0.908  1.0
  O  O16  1  0.298  0.248  0.132  1.0
  O  O17  1  0.351  0.890  0.408  1.0
  O  O18  1  0.202  0.248  0.632  1.0
  O  O19  1  0.381  0.512  0.372  1.0
  O  O20  1  0.452  0.761  0.163  1.0
  O  O21  1  0.548  0.239  0.837  1.0
  O  O22  1  0.619  0.488  0.628  1.0
  O  O23  1  0.798  0.752  0.368  1.0
  O  O24  1  0.649  0.110  0.592  1.0
  O  O25  1  0.702  0.752  0.868  1.0
  O  O26  1  0.851  0.110  0.092  1.0
  O  O27  1  0.881  0.488  0.128  1.0
[/CIF]
.