The crystal structure described by Li2FeP2O7 crystallizes in the orthorhombic Cmm2 space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to one O(7) and two equivalent O(11) atoms. In the second Li site, Li(2) is bonded in a 3-coordinate geometry to one O(8) and two equivalent O(12) atoms. In the third Li site, Li(3) is bonded in a 3-coordinate geometry to one O(5) and two equivalent O(9) atoms. In the fourth Li site, Li(4) is bonded in a 3-coordinate geometry to one O(6) and two equivalent O(10) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(12) and two equivalent O(9) atoms to form FeO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(4)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(10) and two equivalent O(11) atoms to form FeO4 tetrahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(6), and two equivalent O(9) atoms to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Fe(1)O4 tetrahedra. In the second P site, P(2) is bonded to one O(2), one O(5), and two equivalent O(10) atoms to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Fe(2)O4 tetrahedra. In the third P site, P(3) is bonded to one O(3), one O(8), and two equivalent O(11) atoms to form PO4 tetrahedra that share  a cornercorner with one P(3)O4 tetrahedra and corners with two equivalent Fe(2)O4 tetrahedra. In the fourth P site, P(4) is bonded to one O(4), one O(7), and two equivalent O(12) atoms to form PO4 tetrahedra that share  a cornercorner with one P(4)O4 tetrahedra and corners with two equivalent Fe(1)O4 tetrahedra. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent P(2) atoms. In the third O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent P(3) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent P(4) atoms. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Li(3) and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Li(4) and one P(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Li(1) and one P(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Li(2) and one P(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Li(3), one Fe(1), and one P(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Li(4), one Fe(2), and one P(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Li(1), one Fe(2), and one P(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one P(4) atom. is represented by the CIF file [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.063
_cell_length_b   7.843
_cell_length_c   7.850
_cell_angle_alpha   89.540
_cell_angle_beta   89.996
_cell_angle_gamma   90.009
_symmetry_Int_Tables_number   1
_cell_volume   311.667
_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
  Fe  Fe0  1  0.001  1.000  1.000  1.0
  Fe  Fe1  1  0.002  0.500  0.500  1.0
  Li  Li2  1  0.471  0.273  0.773  1.0
  Li  Li3  1  0.530  0.774  0.726  1.0
  Li  Li4  1  0.530  0.226  0.274  1.0
  Li  Li5  1  0.471  0.727  0.227  1.0
  O  O6  1  0.184  0.500  0.000  1.0
  O  O7  1  0.819  0.000  0.500  1.0
  O  O8  1  0.797  0.653  0.847  1.0
  O  O9  1  0.202  0.153  0.653  1.0
  O  O10  1  0.202  0.847  0.347  1.0
  O  O11  1  0.797  0.347  0.153  1.0
  O  O12  1  0.235  0.805  0.918  1.0
  O  O13  1  0.764  0.078  0.804  1.0
  O  O14  1  0.235  0.581  0.695  1.0
  O  O15  1  0.764  0.304  0.578  1.0
  O  O16  1  0.764  0.696  0.422  1.0
  O  O17  1  0.235  0.419  0.305  1.0
  O  O18  1  0.764  0.922  0.196  1.0
  O  O19  1  0.235  0.195  0.082  1.0
  P  P20  1  0.093  0.640  0.860  1.0
  P  P21  1  0.906  0.139  0.639  1.0
  P  P22  1  0.906  0.861  0.360  1.0
  P  P23  1  0.093  0.360  0.140  1.0
[/CIF]
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The crystal structure described by Li2FeP2O7 crystallizes in the orthorhombic Cmm2 space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to one O(7) and two equivalent O(11) atoms. In the second Li site, Li(2) is bonded in a 3-coordinate geometry to one O(8) and two equivalent O(12) atoms. In the third Li site, Li(3) is bonded in a 3-coordinate geometry to one O(5) and two equivalent O(9) atoms. In the fourth Li site, Li(4) is bonded in a 3-coordinate geometry to one O(6) and two equivalent O(10) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(12) and two equivalent O(9) atoms to form FeO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(4)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(10) and two equivalent O(11) atoms to form FeO4 tetrahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(6), and two equivalent O(9) atoms to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Fe(1)O4 tetrahedra. In the second P site, P(2) is bonded to one O(2), one O(5), and two equivalent O(10) atoms to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Fe(2)O4 tetrahedra. In the third P site, P(3) is bonded to one O(3), one O(8), and two equivalent O(11) atoms to form PO4 tetrahedra that share  a cornercorner with one P(3)O4 tetrahedra and corners with two equivalent Fe(2)O4 tetrahedra. In the fourth P site, P(4) is bonded to one O(4), one O(7), and two equivalent O(12) atoms to form PO4 tetrahedra that share  a cornercorner with one P(4)O4 tetrahedra and corners with two equivalent Fe(1)O4 tetrahedra. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent P(2) atoms. In the third O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent P(3) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent P(4) atoms. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Li(3) and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Li(4) and one P(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Li(1) and one P(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Li(2) and one P(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Li(3), one Fe(1), and one P(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Li(4), one Fe(2), and one P(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Li(1), one Fe(2), and one P(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one P(4) atom. is represented by the CIF file [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.063
_cell_length_b   7.843
_cell_length_c   7.850
_cell_angle_alpha   89.540
_cell_angle_beta   89.996
_cell_angle_gamma   90.009
_symmetry_Int_Tables_number   1
_cell_volume   311.667
_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
  Fe  Fe0  1  0.001  1.000  1.000  1.0
  Fe  Fe1  1  0.002  0.500  0.500  1.0
  Li  Li2  1  0.471  0.273  0.773  1.0
  Li  Li3  1  0.530  0.774  0.726  1.0
  Li  Li4  1  0.530  0.226  0.274  1.0
  Li  Li5  1  0.471  0.727  0.227  1.0
  O  O6  1  0.184  0.500  0.000  1.0
  O  O7  1  0.819  0.000  0.500  1.0
  O  O8  1  0.797  0.653  0.847  1.0
  O  O9  1  0.202  0.153  0.653  1.0
  O  O10  1  0.202  0.847  0.347  1.0
  O  O11  1  0.797  0.347  0.153  1.0
  O  O12  1  0.235  0.805  0.918  1.0
  O  O13  1  0.764  0.078  0.804  1.0
  O  O14  1  0.235  0.581  0.695  1.0
  O  O15  1  0.764  0.304  0.578  1.0
  O  O16  1  0.764  0.696  0.422  1.0
  O  O17  1  0.235  0.419  0.305  1.0
  O  O18  1  0.764  0.922  0.196  1.0
  O  O19  1  0.235  0.195  0.082  1.0
  P  P20  1  0.093  0.640  0.860  1.0
  P  P21  1  0.906  0.139  0.639  1.0
  P  P22  1  0.906  0.861  0.360  1.0
  P  P23  1  0.093  0.360  0.140  1.0
[/CIF]
.