data_Ca3S
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.27
_cell_length_b   6.27
_cell_length_c   6.27
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca3S
_chemical_formula_sum   'Ca6 S2'
_cell_volume   246.66
_cell_formula_units_Z   2
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  0.57  0.0  0.14  1.0
  Ca  Ca1  1  0.7  0.0  0.14  1.0
  Ca  Ca2  1  0.14  0.57  0.0  1.0
  Ca  Ca3  1  0.14  0.7  0.0  1.0
  Ca  Ca4  1  0.0  0.14  0.7  1.0
  Ca  Ca5  1  0.0  0.14  0.57  1.0
  S  S6  1  0.14  0.14  0.14  1.0
  S  S7  1  0.0  0.0  0.0  1.0

data_Ca3S
_symmetry_space_group_name_H-M   R3
_cell_length_a   8.87
_cell_length_b   8.87
_cell_length_c   10.86
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Ca3S
_chemical_formula_sum   'Ca18 S6'
_cell_volume   739.99
_cell_formula_units_Z   6
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  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+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
  Ca  Ca0  9  0.05  0.24  0.95  1.0
  Ca  Ca1  9  0.1  0.33  0.9  1.0
  S  S2  3  0.0  0.0  0.0  1.0
  S  S3  3  0.0  0.0  0.14  1.0

Ca Ca Ca Ca Ca Ca S S
Ca3S crystallizes in the trigonal R3 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted linear geometry to one Ca(2) and one S(1) atom. The Ca(1)-Ca(2) bond length is 0.85 Å. The Ca(1)-S(1) bond length is 2.84 Å. In the second Ca site, Ca(2) is bonded in a distorted single-bond geometry to one Ca(1) and one S(2) atom. The Ca(2)-S(2) bond length is 2.04 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded in a tetrahedral geometry to three equivalent Ca(1) and one S(2) atom. The S(1)-S(2) bond length is 1.47 Å. In the second S site, S(2) is bonded in a tetrahedral geometry to three equivalent Ca(2) and one S(1) atom.