data_BeAlSi4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.98
_cell_length_b   4.98
_cell_length_c   4.98
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BeAlSi4
_chemical_formula_sum   'Be1 Al1 Si4'
_cell_volume   87.39
_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
  Be  Be1  1  0.0  0.0  0.0  1.0
  Al  Al0  1  0.28  0.28  0.28  1.0
  Si  Si2  1  0.41  0.41  0.64  1.0
  Si  Si3  1  0.41  0.64  0.41  1.0
  Si  Si4  1  0.64  0.41  0.41  1.0
  Si  Si5  1  0.64  0.64  0.64  1.0

data_BeAlSi4
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.98
_cell_length_b   4.98
_cell_length_c   12.2
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   BeAlSi4
_chemical_formula_sum   'Be3 Al3 Si12'
_cell_volume   262.16
_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
  Be  Be0  3  0.0  0.0  0.0  1.0
  Al  Al1  3  0.0  0.0  0.72  1.0
  Si  Si2  9  0.08  0.15  0.52  1.0
  Si  Si3  3  0.0  0.0  0.36  1.0

Be Al Si Si Si Si
BeAlSi4 crystallizes in the trigonal R3m space group. The structure consists of three 7440-41-7 atoms inside a AlSi4 framework. In the AlSi4 framework, Al(1) is bonded in a 9-coordinate geometry to three equivalent Si(2) and six equivalent Si(1) atoms. All Al(1)-Si(2) bond lengths are 2.89 Å. There are three shorter (2.53 Å) and three longer (2.74 Å) Al(1)-Si(1) bond lengths. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a 6-coordinate geometry to three equivalent Al(1) and three equivalent Si(1) atoms. All Si(2)-Si(1) bond lengths are 2.00 Å. In the second Si site, Si(1) is bonded in a 2-coordinate geometry to two equivalent Al(1), one Si(2), and two equivalent Si(1) atoms. Both Si(1)-Si(1) bond lengths are 1.16 Å.