data_ZrNpSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   4.76
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   ZrNpSi2
_chemical_formula_sum   'Zr1 Np1 Si2'
_cell_volume   76.18
_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
  Zr  Zr3  1  0.0  0.0  0.0  1.0
  Np  Np0  1  0.36  0.36  0.36  1.0
  Si  Si1  1  0.68  0.68  0.68  1.0
  Si  Si2  1  0.05  0.05  0.05  1.0

data_ZrNpSi2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   11.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   ZrNpSi2
_chemical_formula_sum   'Zr3 Np3 Si6'
_cell_volume   228.54
_cell_formula_units_Z   3
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
  Zr  Zr0  3  0.0  0.0  0.0  1.0
  Np  Np1  3  0.0  0.0  0.64  1.0
  Si  Si2  3  0.0  0.0  0.32  1.0
  Si  Si3  3  0.0  0.0  0.95  1.0

Zr Np Si Si
NpZrSi2 crystallizes in the trigonal R3m space group. Np(1) is bonded in a 11-coordinate geometry to three equivalent Zr(1), four equivalent Si(1), and four equivalent Si(2) atoms. All Np(1)-Zr(1) bond lengths are 2.77 Å. There are three shorter (2.75 Å) and one longer (3.70 Å) Np(1)-Si(1) bond length. There are three shorter (2.75 Å) and one longer (3.70 Å) Np(1)-Si(2) bond length. Zr(1) is bonded in a single-bond geometry to three equivalent Np(1), one Si(2), and three equivalent Si(1) atoms. The Zr(1)-Si(2) bond length is 0.55 Å. All Zr(1)-Si(1) bond lengths are 2.75 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to four equivalent Np(1) and three equivalent Zr(1) atoms. In the second Si site, Si(2) is bonded in a single-bond geometry to four equivalent Np(1) and one Zr(1) atom.