The compound described by Ba2CuSi2O7 crystallizes in the monoclinic C2/c space group. Ba(1) is bonded in a 8-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(4), and three equivalent O(2) atoms. Cu(1) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form CuO4 tetrahedra that share 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 two equivalent Cu(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Cu(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to three equivalent Ba(1) and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Cu(1), and one Si(1) atom. is represented by the CIF card [CIF]
data_Ba2CuSi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.855
_cell_length_b   6.855
_cell_length_c   8.660
_cell_angle_alpha   77.447
_cell_angle_beta   77.447
_cell_angle_gamma   101.640
_symmetry_Int_Tables_number   1
_cell_volume   374.195
_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  0.733  0.813  0.973  1.0
  Ba  Ba1  1  0.813  0.733  0.473  1.0
  Ba  Ba2  1  0.187  0.267  0.527  1.0
  Ba  Ba3  1  0.267  0.187  0.027  1.0
  Cu  Cu4  1  0.737  0.263  0.250  1.0
  Cu  Cu5  1  0.263  0.737  0.750  1.0
  Si  Si6  1  0.160  0.615  0.140  1.0
  Si  Si7  1  0.840  0.385  0.860  1.0
  Si  Si8  1  0.385  0.840  0.360  1.0
  Si  Si9  1  0.615  0.160  0.640  1.0
  O  O10  1  0.965  0.627  0.765  1.0
  O  O11  1  0.035  0.373  0.235  1.0
  O  O12  1  0.776  0.016  0.637  1.0
  O  O13  1  0.331  0.669  0.250  1.0
  O  O14  1  0.627  0.312  0.461  1.0
  O  O15  1  0.016  0.776  0.137  1.0
  O  O16  1  0.312  0.627  0.961  1.0
  O  O17  1  0.224  0.984  0.363  1.0
  O  O18  1  0.669  0.331  0.750  1.0
  O  O19  1  0.373  0.688  0.539  1.0
  O  O20  1  0.373  0.035  0.735  1.0
  O  O21  1  0.627  0.965  0.265  1.0
  O  O22  1  0.984  0.224  0.863  1.0
  O  O23  1  0.688  0.373  0.039  1.0
[/CIF]
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The compound described by Ba2CuSi2O7 crystallizes in the monoclinic C2/c space group. Ba(1) is bonded in a 8-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(4), and three equivalent O(2) atoms. Cu(1) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form CuO4 tetrahedra that share 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 two equivalent Cu(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Cu(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to three equivalent Ba(1) and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Cu(1), and one Si(1) atom. is represented by the CIF card [CIF]
data_Ba2CuSi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.855
_cell_length_b   6.855
_cell_length_c   8.660
_cell_angle_alpha   77.447
_cell_angle_beta   77.447
_cell_angle_gamma   101.640
_symmetry_Int_Tables_number   1
_cell_volume   374.195
_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  0.733  0.813  0.973  1.0
  Ba  Ba1  1  0.813  0.733  0.473  1.0
  Ba  Ba2  1  0.187  0.267  0.527  1.0
  Ba  Ba3  1  0.267  0.187  0.027  1.0
  Cu  Cu4  1  0.737  0.263  0.250  1.0
  Cu  Cu5  1  0.263  0.737  0.750  1.0
  Si  Si6  1  0.160  0.615  0.140  1.0
  Si  Si7  1  0.840  0.385  0.860  1.0
  Si  Si8  1  0.385  0.840  0.360  1.0
  Si  Si9  1  0.615  0.160  0.640  1.0
  O  O10  1  0.965  0.627  0.765  1.0
  O  O11  1  0.035  0.373  0.235  1.0
  O  O12  1  0.776  0.016  0.637  1.0
  O  O13  1  0.331  0.669  0.250  1.0
  O  O14  1  0.627  0.312  0.461  1.0
  O  O15  1  0.016  0.776  0.137  1.0
  O  O16  1  0.312  0.627  0.961  1.0
  O  O17  1  0.224  0.984  0.363  1.0
  O  O18  1  0.669  0.331  0.750  1.0
  O  O19  1  0.373  0.688  0.539  1.0
  O  O20  1  0.373  0.035  0.735  1.0
  O  O21  1  0.627  0.965  0.265  1.0
  O  O22  1  0.984  0.224  0.863  1.0
  O  O23  1  0.688  0.373  0.039  1.0
[/CIF]
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