The material structure described by Na2MnO2 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a distorted trigonal planar geometry to one O(1), one O(2), and one O(4) atom. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing MnO4 trigonal pyramids. In the second Mn site, Mn(2) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form a mixture of distorted corner and edge-sharing MnO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Na(4), and two equivalent Mn(2) atoms. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), two equivalent Na(4), and one Mn(1) atom to form ONa5Mn octahedra that share corners with two equivalent O(2)Na5Mn octahedra, corners with three equivalent O(4)Na4Mn2 octahedra, and  an edgeedge with one O(4)Na4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 41-50°. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Mn(2), and two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded to one Na(2), one Na(3), two equivalent Na(1), one Mn(1), and one Mn(2) atom to form ONa4Mn2 octahedra that share corners with two equivalent O(4)Na4Mn2 octahedra, corners with three equivalent O(2)Na5Mn octahedra, and  an edgeedge with one O(2)Na5Mn octahedra. The corner-sharing octahedral tilt angles range from 47-60°. is represented by the CIF file [CIF]
data_Na2MnO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.478
_cell_length_b   8.747
_cell_length_c   15.430
_cell_angle_alpha   56.294
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   615.046
_cell_formula_units_Z   8
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
  Na  Na0  1  0.991  0.643  0.736  1.0
  Na  Na1  1  0.428  0.600  0.865  1.0
  Na  Na2  1  0.910  0.865  0.457  1.0
  Na  Na3  1  0.993  0.091  0.193  1.0
  Na  Na4  1  0.493  0.909  0.307  1.0
  Na  Na5  1  0.410  0.135  0.043  1.0
  Na  Na6  1  0.928  0.400  0.635  1.0
  Na  Na7  1  0.491  0.357  0.764  1.0
  Na  Na8  1  0.509  0.643  0.236  1.0
  Na  Na9  1  0.072  0.600  0.365  1.0
  Na  Na10  1  0.590  0.865  0.957  1.0
  Na  Na11  1  0.507  0.091  0.693  1.0
  Na  Na12  1  0.007  0.909  0.807  1.0
  Na  Na13  1  0.090  0.135  0.543  1.0
  Na  Na14  1  0.572  0.400  0.135  1.0
  Na  Na15  1  0.009  0.357  0.264  1.0
  Mn  Mn16  1  0.495  0.851  0.612  1.0
  Mn  Mn17  1  0.956  0.374  0.971  1.0
  Mn  Mn18  1  0.456  0.626  0.529  1.0
  Mn  Mn19  1  0.995  0.149  0.888  1.0
  Mn  Mn20  1  0.005  0.851  0.112  1.0
  Mn  Mn21  1  0.544  0.374  0.471  1.0
  Mn  Mn22  1  0.044  0.626  0.029  1.0
  Mn  Mn23  1  0.505  0.149  0.388  1.0
  O  O24  1  0.193  0.375  0.081  1.0
  O  O25  1  0.735  0.136  0.292  1.0
  O  O26  1  0.326  0.889  0.470  1.0
  O  O27  1  0.699  0.633  0.633  1.0
  O  O28  1  0.199  0.367  0.867  1.0
  O  O29  1  0.826  0.111  0.030  1.0
  O  O30  1  0.307  0.375  0.581  1.0
  O  O31  1  0.235  0.864  0.208  1.0
  O  O32  1  0.765  0.136  0.792  1.0
  O  O33  1  0.693  0.625  0.419  1.0
  O  O34  1  0.174  0.889  0.970  1.0
  O  O35  1  0.801  0.633  0.133  1.0
  O  O36  1  0.301  0.367  0.367  1.0
  O  O37  1  0.674  0.111  0.530  1.0
  O  O38  1  0.265  0.864  0.708  1.0
  O  O39  1  0.807  0.625  0.919  1.0
[/CIF]
.
The material structure described by Na2MnO2 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a distorted trigonal planar geometry to one O(1), one O(2), and one O(4) atom. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing MnO4 trigonal pyramids. In the second Mn site, Mn(2) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form a mixture of distorted corner and edge-sharing MnO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Na(4), and two equivalent Mn(2) atoms. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), two equivalent Na(4), and one Mn(1) atom to form ONa5Mn octahedra that share corners with two equivalent O(2)Na5Mn octahedra, corners with three equivalent O(4)Na4Mn2 octahedra, and  an edgeedge with one O(4)Na4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 41-50°. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Mn(2), and two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded to one Na(2), one Na(3), two equivalent Na(1), one Mn(1), and one Mn(2) atom to form ONa4Mn2 octahedra that share corners with two equivalent O(4)Na4Mn2 octahedra, corners with three equivalent O(2)Na5Mn octahedra, and  an edgeedge with one O(2)Na5Mn octahedra. The corner-sharing octahedral tilt angles range from 47-60°. is represented by the CIF file [CIF]
data_Na2MnO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.478
_cell_length_b   8.747
_cell_length_c   15.430
_cell_angle_alpha   56.294
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   615.046
_cell_formula_units_Z   8
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
  Na  Na0  1  0.991  0.643  0.736  1.0
  Na  Na1  1  0.428  0.600  0.865  1.0
  Na  Na2  1  0.910  0.865  0.457  1.0
  Na  Na3  1  0.993  0.091  0.193  1.0
  Na  Na4  1  0.493  0.909  0.307  1.0
  Na  Na5  1  0.410  0.135  0.043  1.0
  Na  Na6  1  0.928  0.400  0.635  1.0
  Na  Na7  1  0.491  0.357  0.764  1.0
  Na  Na8  1  0.509  0.643  0.236  1.0
  Na  Na9  1  0.072  0.600  0.365  1.0
  Na  Na10  1  0.590  0.865  0.957  1.0
  Na  Na11  1  0.507  0.091  0.693  1.0
  Na  Na12  1  0.007  0.909  0.807  1.0
  Na  Na13  1  0.090  0.135  0.543  1.0
  Na  Na14  1  0.572  0.400  0.135  1.0
  Na  Na15  1  0.009  0.357  0.264  1.0
  Mn  Mn16  1  0.495  0.851  0.612  1.0
  Mn  Mn17  1  0.956  0.374  0.971  1.0
  Mn  Mn18  1  0.456  0.626  0.529  1.0
  Mn  Mn19  1  0.995  0.149  0.888  1.0
  Mn  Mn20  1  0.005  0.851  0.112  1.0
  Mn  Mn21  1  0.544  0.374  0.471  1.0
  Mn  Mn22  1  0.044  0.626  0.029  1.0
  Mn  Mn23  1  0.505  0.149  0.388  1.0
  O  O24  1  0.193  0.375  0.081  1.0
  O  O25  1  0.735  0.136  0.292  1.0
  O  O26  1  0.326  0.889  0.470  1.0
  O  O27  1  0.699  0.633  0.633  1.0
  O  O28  1  0.199  0.367  0.867  1.0
  O  O29  1  0.826  0.111  0.030  1.0
  O  O30  1  0.307  0.375  0.581  1.0
  O  O31  1  0.235  0.864  0.208  1.0
  O  O32  1  0.765  0.136  0.792  1.0
  O  O33  1  0.693  0.625  0.419  1.0
  O  O34  1  0.174  0.889  0.970  1.0
  O  O35  1  0.801  0.633  0.133  1.0
  O  O36  1  0.301  0.367  0.367  1.0
  O  O37  1  0.674  0.111  0.530  1.0
  O  O38  1  0.265  0.864  0.708  1.0
  O  O39  1  0.807  0.625  0.919  1.0
[/CIF]
.