data_MgNp2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.01
_cell_length_b   5.01
_cell_length_c   5.01
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgNp2Si
_chemical_formula_sum   'Mg1 Np2 Si1'
_cell_volume   88.69
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Np  Np1  1  0.31  0.31  0.31  1.0
  Np  Np2  1  0.77  0.77  0.77  1.0
  Si  Si3  1  0.54  0.54  0.54  1.0

data_MgNp2Si
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.01
_cell_length_b   5.01
_cell_length_c   12.26
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MgNp2Si
_chemical_formula_sum   'Mg3 Np6 Si3'
_cell_volume   266.07
_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
  Mg  Mg0  3  0.0  0.0  0.0  1.0
  Np  Np1  3  0.0  0.0  0.23  1.0
  Np  Np2  3  0.0  0.0  0.69  1.0
  Si  Si3  3  0.0  0.0  0.46  1.0

Mg Np Np Si
MgNp2Si is Heusler structured and crystallizes in the trigonal R3m space group. Mg(1) is bonded in a 11-coordinate geometry to four equivalent Np(1), four equivalent Np(2), and three equivalent Si(1) atoms. There are three shorter (2.90 Å) and one longer (3.79 Å) Mg(1)-Np(1) bond length. There is one shorter (2.82 Å) and three longer (3.15 Å) Mg(1)-Np(2) bond lengths. All Mg(1)-Si(1) bond lengths are 3.28 Å. There are two inequivalent Np sites. In the first Np site, Np(1) is bonded in a 7-coordinate geometry to four equivalent Mg(1) and four equivalent Si(1) atoms. There is one shorter (2.82 Å) and three longer (3.15 Å) Np(1)-Si(1) bond lengths. In the second Np site, Np(2) is bonded in a 8-coordinate geometry to four equivalent Mg(1) and four equivalent Si(1) atoms. There is one shorter (2.82 Å) and three longer (3.15 Å) Np(2)-Si(1) bond lengths. Si(1) is bonded in a distorted body-centered cubic geometry to three equivalent Mg(1), four equivalent Np(1), and four equivalent Np(2) atoms.