The material structure described by Li5Mn3O8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form LiO6 octahedra that share corners with three equivalent Li(3)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra,  an edgeedge with one Li(3)O6 octahedra,  an edgeedge with one Mn(2)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. In the second Li site, Li(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form LiO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Li(3)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the third Li site, Li(3) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form LiO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-11°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Li(2)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Li(3)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the second Mn site, Mn(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Li(3)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), two equivalent Li(2), one Mn(2), and two equivalent Mn(1) atoms to form OLi3Mn3 octahedra that share corners with three equivalent O(1)Li3Mn3 octahedra, corners with three equivalent O(3)Li4Mn2 octahedra,  an edgeedge with one O(1)Li3Mn3 octahedra, edges with three equivalent O(3)Li4Mn2 octahedra, and edges with eight equivalent O(2)Li4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second O site, O(2) is bonded to one Li(2), one Li(3), two equivalent Li(1), one Mn(1), and one Mn(2) atom to form OLi4Mn2 octahedra that share corners with six equivalent O(2)Li4Mn2 octahedra, edges with four equivalent O(1)Li3Mn3 octahedra, edges with four equivalent O(2)Li4Mn2 octahedra, and edges with four equivalent O(3)Li4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the third O site, O(3) is bonded to one Li(1), one Li(3), two equivalent Li(2), and two equivalent Mn(1) atoms to form OLi4Mn2 octahedra that share corners with three equivalent O(1)Li3Mn3 octahedra, corners with three equivalent O(3)Li4Mn2 octahedra,  an edgeedge with one O(3)Li4Mn2 octahedra, edges with three equivalent O(1)Li3Mn3 octahedra, and edges with eight equivalent O(2)Li4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. is represented by the CIF file [CIF]
data_Li5Mn3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.133
_cell_length_b   5.765
_cell_length_c   5.918
_cell_angle_alpha   60.850
_cell_angle_beta   71.576
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   142.603
_cell_formula_units_Z   1
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  0.499  0.246  0.009  1.0
  Li  Li1  1  0.500  0.238  0.500  1.0
  Li  Li2  1  0.500  0.762  0.500  1.0
  Li  Li3  1  0.501  0.754  0.991  1.0
  Li  Li4  1  0.000  1.000  0.500  1.0
  Mn  Mn5  1  1.000  0.000  0.000  1.0
  Mn  Mn6  1  0.000  0.500  0.500  1.0
  Mn  Mn7  1  0.000  0.500  1.000  1.0
  O  O8  1  0.238  0.358  0.784  1.0
  O  O9  1  0.215  0.391  0.241  1.0
  O  O10  1  0.215  0.868  0.241  1.0
  O  O11  1  0.229  0.863  0.774  1.0
  O  O12  1  0.771  0.137  0.226  1.0
  O  O13  1  0.785  0.132  0.758  1.0
  O  O14  1  0.785  0.609  0.759  1.0
  O  O15  1  0.762  0.642  0.216  1.0
[/CIF]
.
The material structure described by Li5Mn3O8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form LiO6 octahedra that share corners with three equivalent Li(3)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra,  an edgeedge with one Li(3)O6 octahedra,  an edgeedge with one Mn(2)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. In the second Li site, Li(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form LiO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Li(3)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the third Li site, Li(3) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form LiO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-11°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Li(2)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Li(3)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the second Mn site, Mn(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Li(3)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), two equivalent Li(2), one Mn(2), and two equivalent Mn(1) atoms to form OLi3Mn3 octahedra that share corners with three equivalent O(1)Li3Mn3 octahedra, corners with three equivalent O(3)Li4Mn2 octahedra,  an edgeedge with one O(1)Li3Mn3 octahedra, edges with three equivalent O(3)Li4Mn2 octahedra, and edges with eight equivalent O(2)Li4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second O site, O(2) is bonded to one Li(2), one Li(3), two equivalent Li(1), one Mn(1), and one Mn(2) atom to form OLi4Mn2 octahedra that share corners with six equivalent O(2)Li4Mn2 octahedra, edges with four equivalent O(1)Li3Mn3 octahedra, edges with four equivalent O(2)Li4Mn2 octahedra, and edges with four equivalent O(3)Li4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the third O site, O(3) is bonded to one Li(1), one Li(3), two equivalent Li(2), and two equivalent Mn(1) atoms to form OLi4Mn2 octahedra that share corners with three equivalent O(1)Li3Mn3 octahedra, corners with three equivalent O(3)Li4Mn2 octahedra,  an edgeedge with one O(3)Li4Mn2 octahedra, edges with three equivalent O(1)Li3Mn3 octahedra, and edges with eight equivalent O(2)Li4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. is represented by the CIF file [CIF]
data_Li5Mn3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.133
_cell_length_b   5.765
_cell_length_c   5.918
_cell_angle_alpha   60.850
_cell_angle_beta   71.576
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   142.603
_cell_formula_units_Z   1
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  0.499  0.246  0.009  1.0
  Li  Li1  1  0.500  0.238  0.500  1.0
  Li  Li2  1  0.500  0.762  0.500  1.0
  Li  Li3  1  0.501  0.754  0.991  1.0
  Li  Li4  1  0.000  1.000  0.500  1.0
  Mn  Mn5  1  1.000  0.000  0.000  1.0
  Mn  Mn6  1  0.000  0.500  0.500  1.0
  Mn  Mn7  1  0.000  0.500  1.000  1.0
  O  O8  1  0.238  0.358  0.784  1.0
  O  O9  1  0.215  0.391  0.241  1.0
  O  O10  1  0.215  0.868  0.241  1.0
  O  O11  1  0.229  0.863  0.774  1.0
  O  O12  1  0.771  0.137  0.226  1.0
  O  O13  1  0.785  0.132  0.758  1.0
  O  O14  1  0.785  0.609  0.759  1.0
  O  O15  1  0.762  0.642  0.216  1.0
[/CIF]
.