The B21 (CO) Structure

Last modified 18 April 2001

You can now

• see the structure from several perspectives;
• examine the structure with an external viewer; or
• download the coordinates of the atoms in these pictures in XYZ format.

The CO molecules sit on the sites of an fcc lattice, however each of the four molecules in the unit cell is oriented differently. Note that this structure has the identical symmetry and Wyckoff positions as the FeSi (B20) structure, except that the atoms are closer together.

• Prototype: CO
• Pearson Symbol: cP8
• Strukturbericht Designation: B21
• Space Group: P2₁3 (Cartesian and lattice coordinate listings available)
• Number: 198
• Primitive Vectors:
  • A₁ = a X
  • A₂ = a Y
  • A₃ = a Z
• Basis Vectors:

  B1	=	x1 aX + x1 aY + x1 aZ	(4a)	(C)
  B2	=	(½ + x1) aX + (½ - x1) aY - x1 aZ	(4a)	(C)
  B3	=	- x1 aX + (½ + x1) aY + (½ - x1) aZ	(4a)	(C)
  B4	=	(½ - x1) aX - x1 aY + (½ + x1) aZ	(4a)	(C)
  B5	=	x2 aX + x2 aY + x2 aZ	(4a)	(O)
  B6	=	(½ + x2) aX + (½ - x2) aY - x2 aZ	(4a)	(O)
  B7	=	- x2 aX + (½ + x2) aY + (½ - x2) aZ	(4a)	(O)
  B8	=	(½ - x2) aX - x2 aY + (½ + x2) aZ	(4a)	(O)

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