The compound described by CaCO4 crystallizes in the trigonal P3_1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(11), one O(5), one O(6), one O(7), one O(9), and two equivalent O(8) atoms to form corner-sharing CaO7 pentagonal bipyramids. In the second Ca site, Ca(2) is bonded to one O(1), one O(12), one O(4), one O(5), one O(6), and two equivalent O(2) atoms to form corner-sharing CaO7 pentagonal bipyramids. In the third Ca site, Ca(3) is bonded to one O(12), one O(3), one O(4), one O(7), one O(9), and two equivalent O(10) atoms to form distorted corner-sharing CaO7 pentagonal bipyramids. There are three inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(11), one O(5), and one O(6) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(1), one O(12), and one O(4) atom. In the third C site, C(3) is bonded in a trigonal planar geometry to one O(3), one O(7), and one O(9) atom. There are twelve inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one C(1) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one C(3) atom. In the third O site, O(8) is bonded in a bent 150 degrees geometry to two equivalent Ca(1) atoms. In the fourth O site, O(9) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one C(3) atom. In the fifth O site, O(10) is bonded in a bent 150 degrees geometry to two equivalent Ca(3) atoms. In the sixth O site, O(11) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one C(1) atom. In the seventh O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Ca(2) and one C(2) atom. In the eighth O site, O(12) is bonded in a 3-coordinate geometry to one Ca(2), one Ca(3), and one C(2) atom. In the ninth O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Ca(2) atoms. In the tenth O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ca(3) and one C(3) atom. In the eleventh O site, O(4) is bonded in a 3-coordinate geometry to one Ca(2), one Ca(3), and one C(2) atom. In the twelfth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one C(1) atom. is represented by the CIF file [CIF]
data_CaCO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.186
_cell_length_b   11.186
_cell_length_c   8.000
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   866.916
_cell_formula_units_Z   9
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  0.895  0.785  0.705  1.0
  Ca  Ca1  1  0.215  0.109  0.039  1.0
  Ca  Ca2  1  0.891  0.105  0.372  1.0
  Ca  Ca3  1  0.549  0.766  0.075  1.0
  Ca  Ca4  1  0.234  0.782  0.409  1.0
  Ca  Ca5  1  0.218  0.451  0.742  1.0
  Ca  Ca6  1  0.563  0.118  0.740  1.0
  Ca  Ca7  1  0.882  0.445  0.073  1.0
  Ca  Ca8  1  0.555  0.437  0.406  1.0
  C  C9  1  0.835  0.931  0.023  1.0
  C  C10  1  0.069  0.904  0.356  1.0
  C  C11  1  0.096  0.165  0.689  1.0
  C  C12  1  0.399  0.830  0.764  1.0
  C  C13  1  0.170  0.569  0.097  1.0
  C  C14  1  0.431  0.601  0.430  1.0
  C  C15  1  0.503  0.239  0.080  1.0
  C  C16  1  0.761  0.264  0.414  1.0
  C  C17  1  0.736  0.497  0.747  1.0
  O  O18  1  0.315  0.698  0.789  1.0
  O  O19  1  0.302  0.617  0.123  1.0
  O  O20  1  0.383  0.685  0.456  1.0
  O  O21  1  0.430  0.845  0.244  1.0
  O  O22  1  0.155  0.585  0.578  1.0
  O  O23  1  0.415  0.570  0.911  1.0
  O  O24  1  0.653  0.366  0.773  1.0
  O  O25  1  0.634  0.287  0.106  1.0
  O  O26  1  0.713  0.347  0.440  1.0
  O  O27  1  0.511  0.891  0.852  1.0
  O  O28  1  0.109  0.619  0.185  1.0
  O  O29  1  0.381  0.489  0.519  1.0
  O  O30  1  0.770  0.819  0.936  1.0
  O  O31  1  0.181  0.952  0.270  1.0
  O  O32  1  0.048  0.230  0.603  1.0
  O  O33  1  0.772  0.963  0.133  1.0
  O  O34  1  0.037  0.808  0.467  1.0
  O  O35  1  0.192  0.228  0.800  1.0
  O  O36  1  0.437  0.285  0.168  1.0
  O  O37  1  0.715  0.153  0.502  1.0
  O  O38  1  0.847  0.563  0.835  1.0
  O  O39  1  0.094  0.916  0.864  1.0
  O  O40  1  0.084  0.178  0.198  1.0
  O  O41  1  0.822  0.906  0.531  1.0
  O  O42  1  0.439  0.143  0.971  1.0
  O  O43  1  0.857  0.296  0.305  1.0
  O  O44  1  0.704  0.561  0.638  1.0
  O  O45  1  0.765  0.254  0.894  1.0
  O  O46  1  0.746  0.510  0.227  1.0
  O  O47  1  0.490  0.235  0.561  1.0
  O  O48  1  0.966  0.016  0.992  1.0
  O  O49  1  0.984  0.951  0.325  1.0
  O  O50  1  0.049  0.034  0.659  1.0
  O  O51  1  0.368  0.896  0.657  1.0
  O  O52  1  0.104  0.472  0.990  1.0
  O  O53  1  0.528  0.632  0.323  1.0
[/CIF]
.
The compound described by CaCO4 crystallizes in the trigonal P3_1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(11), one O(5), one O(6), one O(7), one O(9), and two equivalent O(8) atoms to form corner-sharing CaO7 pentagonal bipyramids. In the second Ca site, Ca(2) is bonded to one O(1), one O(12), one O(4), one O(5), one O(6), and two equivalent O(2) atoms to form corner-sharing CaO7 pentagonal bipyramids. In the third Ca site, Ca(3) is bonded to one O(12), one O(3), one O(4), one O(7), one O(9), and two equivalent O(10) atoms to form distorted corner-sharing CaO7 pentagonal bipyramids. There are three inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(11), one O(5), and one O(6) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(1), one O(12), and one O(4) atom. In the third C site, C(3) is bonded in a trigonal planar geometry to one O(3), one O(7), and one O(9) atom. There are twelve inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one C(1) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one C(3) atom. In the third O site, O(8) is bonded in a bent 150 degrees geometry to two equivalent Ca(1) atoms. In the fourth O site, O(9) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one C(3) atom. In the fifth O site, O(10) is bonded in a bent 150 degrees geometry to two equivalent Ca(3) atoms. In the sixth O site, O(11) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one C(1) atom. In the seventh O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Ca(2) and one C(2) atom. In the eighth O site, O(12) is bonded in a 3-coordinate geometry to one Ca(2), one Ca(3), and one C(2) atom. In the ninth O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Ca(2) atoms. In the tenth O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ca(3) and one C(3) atom. In the eleventh O site, O(4) is bonded in a 3-coordinate geometry to one Ca(2), one Ca(3), and one C(2) atom. In the twelfth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one C(1) atom. is represented by the CIF file [CIF]
data_CaCO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.186
_cell_length_b   11.186
_cell_length_c   8.000
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   866.916
_cell_formula_units_Z   9
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  0.895  0.785  0.705  1.0
  Ca  Ca1  1  0.215  0.109  0.039  1.0
  Ca  Ca2  1  0.891  0.105  0.372  1.0
  Ca  Ca3  1  0.549  0.766  0.075  1.0
  Ca  Ca4  1  0.234  0.782  0.409  1.0
  Ca  Ca5  1  0.218  0.451  0.742  1.0
  Ca  Ca6  1  0.563  0.118  0.740  1.0
  Ca  Ca7  1  0.882  0.445  0.073  1.0
  Ca  Ca8  1  0.555  0.437  0.406  1.0
  C  C9  1  0.835  0.931  0.023  1.0
  C  C10  1  0.069  0.904  0.356  1.0
  C  C11  1  0.096  0.165  0.689  1.0
  C  C12  1  0.399  0.830  0.764  1.0
  C  C13  1  0.170  0.569  0.097  1.0
  C  C14  1  0.431  0.601  0.430  1.0
  C  C15  1  0.503  0.239  0.080  1.0
  C  C16  1  0.761  0.264  0.414  1.0
  C  C17  1  0.736  0.497  0.747  1.0
  O  O18  1  0.315  0.698  0.789  1.0
  O  O19  1  0.302  0.617  0.123  1.0
  O  O20  1  0.383  0.685  0.456  1.0
  O  O21  1  0.430  0.845  0.244  1.0
  O  O22  1  0.155  0.585  0.578  1.0
  O  O23  1  0.415  0.570  0.911  1.0
  O  O24  1  0.653  0.366  0.773  1.0
  O  O25  1  0.634  0.287  0.106  1.0
  O  O26  1  0.713  0.347  0.440  1.0
  O  O27  1  0.511  0.891  0.852  1.0
  O  O28  1  0.109  0.619  0.185  1.0
  O  O29  1  0.381  0.489  0.519  1.0
  O  O30  1  0.770  0.819  0.936  1.0
  O  O31  1  0.181  0.952  0.270  1.0
  O  O32  1  0.048  0.230  0.603  1.0
  O  O33  1  0.772  0.963  0.133  1.0
  O  O34  1  0.037  0.808  0.467  1.0
  O  O35  1  0.192  0.228  0.800  1.0
  O  O36  1  0.437  0.285  0.168  1.0
  O  O37  1  0.715  0.153  0.502  1.0
  O  O38  1  0.847  0.563  0.835  1.0
  O  O39  1  0.094  0.916  0.864  1.0
  O  O40  1  0.084  0.178  0.198  1.0
  O  O41  1  0.822  0.906  0.531  1.0
  O  O42  1  0.439  0.143  0.971  1.0
  O  O43  1  0.857  0.296  0.305  1.0
  O  O44  1  0.704  0.561  0.638  1.0
  O  O45  1  0.765  0.254  0.894  1.0
  O  O46  1  0.746  0.510  0.227  1.0
  O  O47  1  0.490  0.235  0.561  1.0
  O  O48  1  0.966  0.016  0.992  1.0
  O  O49  1  0.984  0.951  0.325  1.0
  O  O50  1  0.049  0.034  0.659  1.0
  O  O51  1  0.368  0.896  0.657  1.0
  O  O52  1  0.104  0.472  0.990  1.0
  O  O53  1  0.528  0.632  0.323  1.0
[/CIF]
.