data_Si3N4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.62
_cell_length_b   5.62
_cell_length_c   5.62
_cell_angle_alpha   109.47
_cell_angle_beta   109.47
_cell_angle_gamma   109.47
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si3N4
_chemical_formula_sum   'Si6 N8'
_cell_volume   136.57
_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  0.62  0.43  0.0  1.0
  Si  Si9  1  0.0  0.62  0.43  1.0
  Si  Si10  1  0.0  0.87  0.81  1.0
  Si  Si11  1  0.43  0.0  0.62  1.0
  Si  Si12  1  0.81  0.0  0.87  1.0
  Si  Si13  1  0.87  0.81  0.0  1.0
  N  N0  1  0.58  0.83  0.42  1.0
  N  N1  1  0.8  0.2  0.45  1.0
  N  N2  1  0.04  0.04  0.04  1.0
  N  N3  1  0.45  0.8  0.2  1.0
  N  N4  1  0.42  0.42  0.42  1.0
  N  N5  1  0.83  0.42  0.58  1.0
  N  N6  1  0.2  0.45  0.8  1.0
  N  N7  1  0.42  0.58  0.83  1.0

data_Si3N4
_symmetry_space_group_name_H-M   R3
_cell_length_a   9.18
_cell_length_b   9.18
_cell_length_c   5.62
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Si3N4
_chemical_formula_sum   'Si18 N24'
_cell_volume   409.72
_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  'x+2/3, y+1/3, z+1/3'
  5  '-y+2/3, x-y+1/3, z+1/3'
  6  '-x+y+2/3, -x+1/3, z+1/3'
  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'
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  0.08  0.73  0.35  1.0
  Si  Si1  9  0.11  0.08  0.89  1.0
  N  N2  9  0.05  0.35  0.15  1.0
  N  N3  9  0.14  0.45  0.28  1.0
  N  N4  3  0.0  0.0  0.04  1.0
  N  N5  3  0.0  0.0  0.42  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 - 0 12 o o - 0 3 o o - 0 5 o o o 0 1 + o o 1 11 - o o 1 2 o o o 1 7 - o o 1 3 o + o 2 8 o + + 3 9 o - o 3 6 o - o 3 4 o o o 4 8 + o + 5 8 + + o 6 9 o o o 6 10 o o o 7 11 o o o 8 10 o o o 10 13 o o o 10 11 o o o 12 13 o o o 