The structure described by BaBe2Si2O7 crystallizes in the orthorhombic Pmn2_1 space group. Ba(1) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(2), and four equivalent O(3) atoms. Be(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form BeO4 tetrahedra that share corners with two equivalent Be(1)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with four equivalent Be(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Ba(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Ba(1), one Be(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one Be(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to two equivalent Be(1) and one Si(1) atom. is represented by the CIF file [CIF]
data_BaBe2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.671
_cell_length_b   4.915
_cell_length_c   11.651
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   267.491
_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
  Ba  Ba0  1  0.011  0.205  0.000  1.0
  Ba  Ba1  1  0.511  0.795  0.500  1.0
  Be  Be2  1  0.517  0.168  0.749  1.0
  Be  Be3  1  0.017  0.832  0.751  1.0
  Be  Be4  1  0.517  0.168  0.251  1.0
  Be  Be5  1  0.017  0.832  0.249  1.0
  Si  Si6  1  0.031  0.325  0.628  1.0
  Si  Si7  1  0.531  0.675  0.872  1.0
  Si  Si8  1  0.531  0.675  0.128  1.0
  Si  Si9  1  0.031  0.325  0.372  1.0
  O  O10  1  0.419  0.773  0.000  1.0
  O  O11  1  0.919  0.227  0.500  1.0
  O  O12  1  0.370  0.269  0.367  1.0
  O  O13  1  0.870  0.731  0.133  1.0
  O  O14  1  0.370  0.269  0.633  1.0
  O  O15  1  0.870  0.731  0.867  1.0
  O  O16  1  0.964  0.644  0.360  1.0
  O  O17  1  0.464  0.356  0.140  1.0
  O  O18  1  0.464  0.356  0.860  1.0
  O  O19  1  0.964  0.644  0.640  1.0
  O  O20  1  0.368  0.867  0.223  1.0
  O  O21  1  0.868  0.133  0.277  1.0
  O  O22  1  0.868  0.133  0.723  1.0
  O  O23  1  0.368  0.867  0.777  1.0
[/CIF]
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The structure described by BaBe2Si2O7 crystallizes in the orthorhombic Pmn2_1 space group. Ba(1) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(2), and four equivalent O(3) atoms. Be(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form BeO4 tetrahedra that share corners with two equivalent Be(1)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with four equivalent Be(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Ba(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Ba(1), one Be(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one Be(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to two equivalent Be(1) and one Si(1) atom. is represented by the CIF file [CIF]
data_BaBe2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.671
_cell_length_b   4.915
_cell_length_c   11.651
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   267.491
_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
  Ba  Ba0  1  0.011  0.205  0.000  1.0
  Ba  Ba1  1  0.511  0.795  0.500  1.0
  Be  Be2  1  0.517  0.168  0.749  1.0
  Be  Be3  1  0.017  0.832  0.751  1.0
  Be  Be4  1  0.517  0.168  0.251  1.0
  Be  Be5  1  0.017  0.832  0.249  1.0
  Si  Si6  1  0.031  0.325  0.628  1.0
  Si  Si7  1  0.531  0.675  0.872  1.0
  Si  Si8  1  0.531  0.675  0.128  1.0
  Si  Si9  1  0.031  0.325  0.372  1.0
  O  O10  1  0.419  0.773  0.000  1.0
  O  O11  1  0.919  0.227  0.500  1.0
  O  O12  1  0.370  0.269  0.367  1.0
  O  O13  1  0.870  0.731  0.133  1.0
  O  O14  1  0.370  0.269  0.633  1.0
  O  O15  1  0.870  0.731  0.867  1.0
  O  O16  1  0.964  0.644  0.360  1.0
  O  O17  1  0.464  0.356  0.140  1.0
  O  O18  1  0.464  0.356  0.860  1.0
  O  O19  1  0.964  0.644  0.640  1.0
  O  O20  1  0.368  0.867  0.223  1.0
  O  O21  1  0.868  0.133  0.277  1.0
  O  O22  1  0.868  0.133  0.723  1.0
  O  O23  1  0.368  0.867  0.777  1.0
[/CIF]
.