The material structure described by MnNiAs crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 11-coordinate geometry to two equivalent Ni(2), four equivalent Ni(1), one As(2), and four equivalent As(1) atoms. In the second Mn site, Mn(2) is bonded in a 11-coordinate geometry to two equivalent Ni(2), four equivalent Ni(1), one As(2), and four equivalent As(1) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to two equivalent Mn(2), four equivalent Mn(1), one Ni(1), one Ni(2), two equivalent As(1), and two equivalent As(2) atoms. In the second Ni site, Ni(2) is bonded in a 12-coordinate geometry to two equivalent Mn(2), four equivalent Mn(1), two equivalent Ni(1), two equivalent As(1), and two equivalent As(2) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to two equivalent Mn(2), four equivalent Mn(1), one Ni(2), and two equivalent Ni(1) atoms. In the second As site, As(2) is bonded in a distorted q6 geometry to one Mn(2), two equivalent Mn(1), two equivalent Ni(2), and four equivalent Ni(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MnNiAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.143
_cell_length_b   6.178
_cell_length_c   3.751
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.192
_symmetry_Int_Tables_number   1
_cell_volume   123.055
_cell_formula_units_Z   3
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
  Mn  Mn0  1  0.416  0.416  0.500  1.0
  Mn  Mn1  1  0.584  1.000  0.500  1.0
  Mn  Mn2  1  0.000  0.585  0.500  1.0
  Ni  Ni3  1  0.754  0.753  0.000  1.0
  Ni  Ni4  1  0.246  0.999  0.000  1.0
  Ni  Ni5  1  0.000  0.246  0.000  1.0
  As  As6  1  0.666  0.333  0.000  1.0
  As  As7  1  0.334  0.667  0.000  1.0
  As  As8  1  1.000  0.002  0.500  1.0
[/CIF]
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The material structure described by MnNiAs crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 11-coordinate geometry to two equivalent Ni(2), four equivalent Ni(1), one As(2), and four equivalent As(1) atoms. In the second Mn site, Mn(2) is bonded in a 11-coordinate geometry to two equivalent Ni(2), four equivalent Ni(1), one As(2), and four equivalent As(1) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to two equivalent Mn(2), four equivalent Mn(1), one Ni(1), one Ni(2), two equivalent As(1), and two equivalent As(2) atoms. In the second Ni site, Ni(2) is bonded in a 12-coordinate geometry to two equivalent Mn(2), four equivalent Mn(1), two equivalent Ni(1), two equivalent As(1), and two equivalent As(2) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to two equivalent Mn(2), four equivalent Mn(1), one Ni(2), and two equivalent Ni(1) atoms. In the second As site, As(2) is bonded in a distorted q6 geometry to one Mn(2), two equivalent Mn(1), two equivalent Ni(2), and four equivalent Ni(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MnNiAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.143
_cell_length_b   6.178
_cell_length_c   3.751
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.192
_symmetry_Int_Tables_number   1
_cell_volume   123.055
_cell_formula_units_Z   3
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
  Mn  Mn0  1  0.416  0.416  0.500  1.0
  Mn  Mn1  1  0.584  1.000  0.500  1.0
  Mn  Mn2  1  0.000  0.585  0.500  1.0
  Ni  Ni3  1  0.754  0.753  0.000  1.0
  Ni  Ni4  1  0.246  0.999  0.000  1.0
  Ni  Ni5  1  0.000  0.246  0.000  1.0
  As  As6  1  0.666  0.333  0.000  1.0
  As  As7  1  0.334  0.667  0.000  1.0
  As  As8  1  1.000  0.002  0.500  1.0
[/CIF]
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