data_CaSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.64
_cell_length_b   3.64
_cell_length_c   4.95
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaSi2
_chemical_formula_sum   'Ca1 Si2'
_cell_volume   65.54
_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
  Ca  Ca0  1  0.0  0.0  0.0  1.0
  Si  Si1  1  0.0  0.82  0.48  1.0
  Si  Si2  1  0.82  0.0  0.48  1.0

data_CaSi2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.14
_cell_length_b   5.14
_cell_length_c   4.95
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   CaSi2
_chemical_formula_sum   'Ca2 Si4'
_cell_volume   131.08
_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
  Ca  Ca0  2  0.0  0.0  0.0  1.0
  Si  Si1  4  0.41  0.41  0.48  1.0

Ca Si Si
Ca Si Si 0 2 - o - 0 2 - o o 0 1 o - - 0 1 o - o 1 2 - + o 