The crystal structure described by LiFeSi2O6 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(4) atoms. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to two equivalent O(5) and two equivalent O(6) atoms. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form FeO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Fe(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to two equivalent O(5) and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Fe(1) and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Li(2), one Si(2), and one Si(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(1), and one Si(3) atom. is represented by the CIF file [CIF]
data_LiFe(SiO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.769
_cell_length_b   7.769
_cell_length_c   9.976
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   93.252
_symmetry_Int_Tables_number   1
_cell_volume   601.224
_cell_formula_units_Z   4
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  0.900  0.100  0.250  1.0
  Li  Li1  1  0.399  0.399  0.000  1.0
  Li  Li2  1  0.601  0.601  0.500  1.0
  Li  Li3  1  0.100  0.900  0.750  1.0
  Fe  Fe4  1  0.662  0.154  0.544  1.0
  Fe  Fe5  1  0.846  0.338  0.956  1.0
  Fe  Fe6  1  0.154  0.662  0.456  1.0
  Fe  Fe7  1  0.338  0.846  0.044  1.0
  Si  Si8  1  0.071  0.071  0.500  1.0
  Si  Si9  1  0.367  0.144  0.297  1.0
  Si  Si10  1  0.144  0.367  0.703  1.0
  Si  Si11  1  0.547  0.453  0.750  1.0
  Si  Si12  1  0.453  0.547  0.250  1.0
  Si  Si13  1  0.856  0.633  0.203  1.0
  Si  Si14  1  0.633  0.856  0.797  1.0
  Si  Si15  1  0.929  0.929  0.000  1.0
  O  O16  1  0.630  0.996  0.680  1.0
  O  O17  1  0.873  0.106  0.456  1.0
  O  O18  1  0.501  0.105  0.414  1.0
  O  O19  1  0.169  0.138  0.360  1.0
  O  O20  1  0.138  0.169  0.640  1.0
  O  O21  1  0.894  0.127  0.044  1.0
  O  O22  1  0.412  0.337  0.228  1.0
  O  O23  1  0.620  0.381  0.609  1.0
  O  O24  1  0.619  0.380  0.891  1.0
  O  O25  1  0.004  0.370  0.820  1.0
  O  O26  1  0.337  0.412  0.772  1.0
  O  O27  1  0.105  0.501  0.586  1.0
  O  O28  1  0.895  0.499  0.086  1.0
  O  O29  1  0.663  0.588  0.272  1.0
  O  O30  1  0.996  0.630  0.320  1.0
  O  O31  1  0.381  0.620  0.391  1.0
  O  O32  1  0.380  0.619  0.109  1.0
  O  O33  1  0.588  0.663  0.728  1.0
  O  O34  1  0.106  0.873  0.544  1.0
  O  O35  1  0.862  0.831  0.140  1.0
  O  O36  1  0.831  0.862  0.860  1.0
  O  O37  1  0.499  0.895  0.914  1.0
  O  O38  1  0.127  0.894  0.956  1.0
  O  O39  1  0.370  0.004  0.180  1.0
[/CIF]
.
The crystal structure described by LiFeSi2O6 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(4) atoms. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to two equivalent O(5) and two equivalent O(6) atoms. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form FeO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Fe(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to two equivalent O(5) and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Fe(1) and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Li(2), one Si(2), and one Si(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(1), and one Si(3) atom. is represented by the CIF file [CIF]
data_LiFe(SiO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.769
_cell_length_b   7.769
_cell_length_c   9.976
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   93.252
_symmetry_Int_Tables_number   1
_cell_volume   601.224
_cell_formula_units_Z   4
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  0.900  0.100  0.250  1.0
  Li  Li1  1  0.399  0.399  0.000  1.0
  Li  Li2  1  0.601  0.601  0.500  1.0
  Li  Li3  1  0.100  0.900  0.750  1.0
  Fe  Fe4  1  0.662  0.154  0.544  1.0
  Fe  Fe5  1  0.846  0.338  0.956  1.0
  Fe  Fe6  1  0.154  0.662  0.456  1.0
  Fe  Fe7  1  0.338  0.846  0.044  1.0
  Si  Si8  1  0.071  0.071  0.500  1.0
  Si  Si9  1  0.367  0.144  0.297  1.0
  Si  Si10  1  0.144  0.367  0.703  1.0
  Si  Si11  1  0.547  0.453  0.750  1.0
  Si  Si12  1  0.453  0.547  0.250  1.0
  Si  Si13  1  0.856  0.633  0.203  1.0
  Si  Si14  1  0.633  0.856  0.797  1.0
  Si  Si15  1  0.929  0.929  0.000  1.0
  O  O16  1  0.630  0.996  0.680  1.0
  O  O17  1  0.873  0.106  0.456  1.0
  O  O18  1  0.501  0.105  0.414  1.0
  O  O19  1  0.169  0.138  0.360  1.0
  O  O20  1  0.138  0.169  0.640  1.0
  O  O21  1  0.894  0.127  0.044  1.0
  O  O22  1  0.412  0.337  0.228  1.0
  O  O23  1  0.620  0.381  0.609  1.0
  O  O24  1  0.619  0.380  0.891  1.0
  O  O25  1  0.004  0.370  0.820  1.0
  O  O26  1  0.337  0.412  0.772  1.0
  O  O27  1  0.105  0.501  0.586  1.0
  O  O28  1  0.895  0.499  0.086  1.0
  O  O29  1  0.663  0.588  0.272  1.0
  O  O30  1  0.996  0.630  0.320  1.0
  O  O31  1  0.381  0.620  0.391  1.0
  O  O32  1  0.380  0.619  0.109  1.0
  O  O33  1  0.588  0.663  0.728  1.0
  O  O34  1  0.106  0.873  0.544  1.0
  O  O35  1  0.862  0.831  0.140  1.0
  O  O36  1  0.831  0.862  0.860  1.0
  O  O37  1  0.499  0.895  0.914  1.0
  O  O38  1  0.127  0.894  0.956  1.0
  O  O39  1  0.370  0.004  0.180  1.0
[/CIF]
.