data_Si3N4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.47
_cell_length_b   5.47
_cell_length_c   5.47
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si3N4
_chemical_formula_sum   'Si6 N8'
_cell_volume   115.45
_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
  Si  Si8  1  0.93  0.93  0.93  1.0
  Si  Si9  1  0.0  0.0  0.0  1.0
  Si  Si10  1  0.9  0.83  0.9  1.0
  Si  Si11  1  0.83  0.83  0.83  1.0
  Si  Si12  1  0.83  0.9  0.9  1.0
  Si  Si13  1  0.9  0.9  0.83  1.0
  N  N0  1  0.71  0.89  0.89  1.0
  N  N1  1  0.89  0.71  0.89  1.0
  N  N2  1  0.89  0.89  0.71  1.0
  N  N3  1  0.71  0.71  0.71  1.0
  N  N4  1  0.77  0.95  0.77  1.0
  N  N5  1  0.95  0.77  0.77  1.0
  N  N6  1  0.77  0.77  0.95  1.0
  N  N7  1  0.95  0.95  0.95  1.0

data_Si3N4
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.47
_cell_length_b   5.47
_cell_length_c   13.39
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Si3N4
_chemical_formula_sum   'Si18 N24'
_cell_volume   346.34
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Si  Si0  9  0.05  0.02  0.12  1.0
  Si  Si1  3  0.0  0.0  0.0  1.0
  Si  Si2  3  0.0  0.0  0.07  1.0
  Si  Si3  3  0.0  0.0  0.17  1.0
  N  N4  9  0.06  0.12  0.17  1.0
  N  N5  9  0.12  0.06  0.17  1.0
  N  N6  3  0.0  0.0  0.05  1.0
  N  N7  3  0.0  0.0  0.29  1.0

Si Si Si Si Si Si N N N N N N N N
Si Si Si Si Si Si N N N N N N N N 0 13 o o o 1 13 - - - 2 4 o o o 2 5 o o o 2 3 o o o 3 12 o o o 3 10 o o o 3 6 o o o 3 11 o o o 3 7 o o o 3 8 o o o 3 5 o o o 3 4 o o o 3 9 o o o 4 5 o o o 6 12 o o o 6 10 o o o 6 9 o o o 7 12 o o o 7 11 o o o 7 9 o o o 8 10 o o o 8 11 o o o 8 9 o o o 9 12 o o o 9 11 o o o 9 10 o o o 