The material described by Ca2MnO3 is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded to one O(1) and five equivalent O(2) atoms to form CaO6 octahedra that share  a cornercorner with one Mn(1)O6 octahedra, corners with five equivalent Ca(1)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with eight equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. Mn(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MnO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with eight equivalent Ca(1)O6 octahedra. The corner-sharing octahedra are not tilted. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and four equivalent Mn(1) atoms to form OCa2Mn4 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca2Mn4 octahedra, edges with four equivalent O(1)Ca2Mn4 octahedra, and edges with eight equivalent O(2)Ca5Mn octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to five equivalent Ca(1) and one Mn(1) atom to form OCa5Mn octahedra that share  a cornercorner with one O(1)Ca2Mn4 octahedra, corners with five equivalent O(2)Ca5Mn octahedra, edges with four equivalent O(1)Ca2Mn4 octahedra, and edges with eight equivalent O(2)Ca5Mn octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(1) is bonded to two equivalent Ca(1) and four equivalent Mn(1) atoms to form OCa2Mn4 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca2Mn4 octahedra, edges with four equivalent O(1)Ca2Mn4 octahedra, and edges with eight equivalent O(2)Ca5Mn octahedra. The corner-sharing octahedra are not tilted. is represented by the CIF file [CIF]
data_Ca2MnO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.361
_cell_length_b   3.361
_cell_length_c   7.428
_cell_angle_alpha   103.077
_cell_angle_beta   103.077
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   79.515
_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  0.337  0.337  0.675  1.0
  Ca  Ca1  1  0.663  0.663  0.325  1.0
  Mn  Mn2  1  0.000  0.000  0.000  1.0
  O  O3  1  0.500  0.500  0.000  1.0
  O  O4  1  0.839  0.839  0.677  1.0
  O  O5  1  0.161  0.161  0.323  1.0
[/CIF]
.
The material described by Ca2MnO3 is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded to one O(1) and five equivalent O(2) atoms to form CaO6 octahedra that share  a cornercorner with one Mn(1)O6 octahedra, corners with five equivalent Ca(1)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with eight equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. Mn(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MnO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with eight equivalent Ca(1)O6 octahedra. The corner-sharing octahedra are not tilted. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and four equivalent Mn(1) atoms to form OCa2Mn4 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca2Mn4 octahedra, edges with four equivalent O(1)Ca2Mn4 octahedra, and edges with eight equivalent O(2)Ca5Mn octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to five equivalent Ca(1) and one Mn(1) atom to form OCa5Mn octahedra that share  a cornercorner with one O(1)Ca2Mn4 octahedra, corners with five equivalent O(2)Ca5Mn octahedra, edges with four equivalent O(1)Ca2Mn4 octahedra, and edges with eight equivalent O(2)Ca5Mn octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(1) is bonded to two equivalent Ca(1) and four equivalent Mn(1) atoms to form OCa2Mn4 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca2Mn4 octahedra, edges with four equivalent O(1)Ca2Mn4 octahedra, and edges with eight equivalent O(2)Ca5Mn octahedra. The corner-sharing octahedra are not tilted. is represented by the CIF file [CIF]
data_Ca2MnO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.361
_cell_length_b   3.361
_cell_length_c   7.428
_cell_angle_alpha   103.077
_cell_angle_beta   103.077
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   79.515
_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  0.337  0.337  0.675  1.0
  Ca  Ca1  1  0.663  0.663  0.325  1.0
  Mn  Mn2  1  0.000  0.000  0.000  1.0
  O  O3  1  0.500  0.500  0.000  1.0
  O  O4  1  0.839  0.839  0.677  1.0
  O  O5  1  0.161  0.161  0.323  1.0
[/CIF]
.