Crystal Lattice Structures:	Creation Date: 28 Jul 2008
	Last Modified: 28 Jul 2008

SiO₂ P2 Structure

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• This structure is the result of simulations of SiO₂ structures from a potential fitted to the H₆Si₂O₇ molecule. As such, we do not believe it has been seen in nature. It does, however, describe a structure in space group P2 (#3).
• Space Group 3 allows an arbitrary choice of origin for the y coordinate of one of the atoms. The choice is is to set y(Si I) = 0.
• This space group requires more than one Wyckoff position to be filled in order for the structure to exhibit P2 symmetry. For example, if all we have in the unit cell are the Si-I atoms, the space group becomes P2/m, even though the (2e) site has the full set of symmetry operations for space group P2. We need at least one other set of atoms to define this structure.

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• Prototype: SiO₂ (Space Group P2)
• Pearson Symbol: mP12
• Strukturbericht Designation: None
• Space Group: P2 (Cartesian and lattice coordinate listings available)
• Number: 3
• Reference: M. B. Boisen, Jr., G. V. Gibbs, and M. S. T. Bukowinski, Phys. Chem. Minerals 21, 269-284 (1994).
• Primitive Vectors (Unique Monoclinic Axis b):

  A1	=	a X
  A2	=	b Y
  A3	=	c cosβ X + c sinβ Z

• Basis Vectors:

  B1	=	+ x1 A1 + z1 A3	=	+ (x1 a + z1 c cosβ) X + z1 c sinβ Z	(Si-I)	(2e)
  B2	=	- x1 A1 - z1 A3	=	- (x1 a + z1 c cosβ) X - z1 c sinβ Z	(Si-I)	(2e)
  B3	=	+ x2 A1 + y2 A2 + z2 A3	=	+ (x2 a + z2 c cosβ) X + y2 b Y + z2 c sinβ Z	(Si-II)	(2e)
  B4	=	- x2 A1 - y2 A2 - z2 A3	=	- (x2 a + z2 c cosβ) X - y2 b Y - z2 c sinβ Z	(Si-II)	(2e)
  B5	=	y3 A2 + ½ A3	=	½ c cosβ X + y3 b Y + ½ c sinβ Z	(O-I)	(1b)
  B6	=	½ A1 + y4 A2	=	½ a X + y4 b Y	(O-II)	(1c)
  B7	=	+ x5 A1 + y5 A2 + z5 A3	=	+ (x5 a + z5 c cosβ) X + y5 b Y + z5 c sinβ Z	(O-III)	(2e)
  B8	=	- x5 A1 - y5 A2 - z5 A3	=	- (x5 a + z5 c cosβ) X - y5 b Y - z5 c sinβ Z	(O-III)	(2e)
  B9	=	+ x6 A1 + y6 A2 + z6 A3	=	+ (x6 a + z6 c cosβ) X + y6 b Y + z6 c sinβ Z	(O-IV)	(2e)
  B10	=	- x6 A1 - y6 A2 - z6 A3	=	- (x6 a + z6 c cosβ) X - y6 b Y - z6 c sinβ Z	(O-IV)	(2e)

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Structures indexed by: Strukturbericht Symbol Pearson Symbol Space Group Prototype

This is a mirror of an old page created at the Naval Research Laboratory Center for Computational Materials Science The maintained successor is hosted at http://www.aflowlib.org/CrystalDatabase/ and published as M. Mehl et al., Comput. Mater. Sci. 136 (Supp.), S1-S828 (2017).