The material structure described by Li2FeP2O7 crystallizes in the monoclinic P2 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to one O(4), one O(6), and one O(8) atom. In the second Li site, Li(2) is bonded in a 3-coordinate geometry to one O(3), one O(5), and one O(7) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(7) and two equivalent O(8) atoms to form FeO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(5) and two equivalent O(6) atoms to form FeO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one Fe(2)O4 tetrahedra, and  a cornercorner with one P(1)O4 tetrahedra. In the second P site, P(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one Fe(2)O4 tetrahedra, and  a cornercorner with one P(2)O4 tetrahedra. There are eight 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 one Li(2) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Li(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Li(2), one Fe(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Li(1), one Fe(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one P(2) atom. is represented by the CIF file [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.087
_cell_length_b   7.790
_cell_length_c   7.897
_cell_angle_alpha   90.719
_cell_angle_beta   90.001
_cell_angle_gamma   90.001
_symmetry_Int_Tables_number   1
_cell_volume   312.874
_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
  Li  Li0  1  0.531  0.226  0.729  1.0
  Li  Li1  1  0.471  0.272  0.231  1.0
  Li  Li2  1  0.471  0.728  0.769  1.0
  Li  Li3  1  0.531  0.774  0.271  1.0
  Fe  Fe4  1  0.006  0.500  0.500  1.0
  Fe  Fe5  1  0.000  0.000  1.000  1.0
  P  P6  1  0.905  0.139  0.360  1.0
  P  P7  1  0.094  0.360  0.859  1.0
  P  P8  1  0.094  0.640  0.141  1.0
  P  P9  1  0.905  0.861  0.640  1.0
  O  O10  1  0.818  1.000  0.500  1.0
  O  O11  1  0.187  0.500  1.000  1.0
  O  O12  1  0.199  0.153  0.346  1.0
  O  O13  1  0.800  0.348  0.848  1.0
  O  O14  1  0.800  0.652  0.152  1.0
  O  O15  1  0.199  0.847  0.654  1.0
  O  O16  1  0.763  0.074  0.197  1.0
  O  O17  1  0.235  0.193  0.915  1.0
  O  O18  1  0.764  0.305  0.420  1.0
  O  O19  1  0.234  0.420  0.696  1.0
  O  O20  1  0.234  0.579  0.304  1.0
  O  O21  1  0.763  0.695  0.580  1.0
  O  O22  1  0.235  0.807  0.086  1.0
  O  O23  1  0.763  0.926  0.803  1.0
[/CIF]
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The material structure described by Li2FeP2O7 crystallizes in the monoclinic P2 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to one O(4), one O(6), and one O(8) atom. In the second Li site, Li(2) is bonded in a 3-coordinate geometry to one O(3), one O(5), and one O(7) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(7) and two equivalent O(8) atoms to form FeO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(5) and two equivalent O(6) atoms to form FeO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one Fe(2)O4 tetrahedra, and  a cornercorner with one P(1)O4 tetrahedra. In the second P site, P(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one Fe(2)O4 tetrahedra, and  a cornercorner with one P(2)O4 tetrahedra. There are eight 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 one Li(2) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Li(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Li(2), one Fe(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Li(1), one Fe(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one P(2) atom. is represented by the CIF file [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.087
_cell_length_b   7.790
_cell_length_c   7.897
_cell_angle_alpha   90.719
_cell_angle_beta   90.001
_cell_angle_gamma   90.001
_symmetry_Int_Tables_number   1
_cell_volume   312.874
_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
  Li  Li0  1  0.531  0.226  0.729  1.0
  Li  Li1  1  0.471  0.272  0.231  1.0
  Li  Li2  1  0.471  0.728  0.769  1.0
  Li  Li3  1  0.531  0.774  0.271  1.0
  Fe  Fe4  1  0.006  0.500  0.500  1.0
  Fe  Fe5  1  0.000  0.000  1.000  1.0
  P  P6  1  0.905  0.139  0.360  1.0
  P  P7  1  0.094  0.360  0.859  1.0
  P  P8  1  0.094  0.640  0.141  1.0
  P  P9  1  0.905  0.861  0.640  1.0
  O  O10  1  0.818  1.000  0.500  1.0
  O  O11  1  0.187  0.500  1.000  1.0
  O  O12  1  0.199  0.153  0.346  1.0
  O  O13  1  0.800  0.348  0.848  1.0
  O  O14  1  0.800  0.652  0.152  1.0
  O  O15  1  0.199  0.847  0.654  1.0
  O  O16  1  0.763  0.074  0.197  1.0
  O  O17  1  0.235  0.193  0.915  1.0
  O  O18  1  0.764  0.305  0.420  1.0
  O  O19  1  0.234  0.420  0.696  1.0
  O  O20  1  0.234  0.579  0.304  1.0
  O  O21  1  0.763  0.695  0.580  1.0
  O  O22  1  0.235  0.807  0.086  1.0
  O  O23  1  0.763  0.926  0.803  1.0
[/CIF]
.