data_SrCa2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.69
_cell_length_b   3.69
_cell_length_c   10.18
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SrCa2Si
_chemical_formula_sum   'Sr1 Ca2 Si1'
_cell_volume   138.74
_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
  Sr  Sr3  1  0.0  0.0  0.09  1.0
  Ca  Ca0  1  0.85  0.85  0.45  1.0
  Ca  Ca1  1  0.85  0.85  0.73  1.0
  Si  Si2  1  0.0  0.0  0.0  1.0

data_SrCa2Si
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.22
_cell_length_b   5.22
_cell_length_c   10.18
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   SrCa2Si
_chemical_formula_sum   'Sr2 Ca4 Si2'
_cell_volume   277.48
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Sr  Sr0  2  0.0  0.0  0.09  1.0
  Ca  Ca1  2  0.35  0.5  0.45  1.0
  Ca  Ca2  2  0.35  0.5  0.73  1.0
  Si  Si3  2  0.0  0.0  0.0  1.0

Sr Ca Ca Si
SrCa2Si crystallizes in the monoclinic Cm space group. Sr(1) is bonded in a single-bond geometry to one Ca(1) and one Si(1) atom. The Sr(1)-Ca(1) bond length is 3.71 Å. The Sr(1)-Si(1) bond length is 0.91 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one Sr(1), one Ca(2), and four equivalent Ca(1) atoms to form a mixture of edge and corner-sharing CaSrCa5 octahedra. The corner-sharing octahedra are not tilted. The Ca(1)-Ca(2) bond length is 2.94 Å. All Ca(1)-Ca(1) bond lengths are 3.69 Å. In the second Ca site, Ca(2) is bonded in a distorted single-bond geometry to one Ca(1) and one Si(1) atom. The Ca(2)-Si(1) bond length is 2.83 Å. Si(1) is bonded in a single-bond geometry to one Sr(1) and one Ca(2) atom.