Crystal Lattice Structures:	Creation Date:  3 Jul 2008
	Last Modified:  3 Jul 2008

The Orthorhombic Tridymite (SiO₂) Structure

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• 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.
• visualize the structure (Uses the JMOL Applet)

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• As noted in the reference, this data is taken from meteoric SiO₂.
• The z coordinates of the reference have been shifted by ¼ c so that the positions agree with the standard space group tables.

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• Prototype: Orthorhombic Tridymite (SiO₂)
• Pearson Symbol: oC24
• Strukturbericht Designation: None
• Space Group: C222₁ (Cartesian and lattice coordinate listings available)
• Number: 20
• Reference: W. A. Dollase, Acta Cryst. 23 617 (1994).
• Primitive Vectors:

  A1	=	½ a X - ½ b Y
  A2	=	½ a X + ½ b Y
  A3	=	c Z

• Basis Vectors:

  B1	=	+ x1 A1 + x1 A2	=	+ x1 a X	(O-I)	(4a)
  B2	=	- x1 A1 - x1 A2 + ½ A3	=	- x1 a X + ½ c Z	(O-I)	(4a)
  B3	=	- y2 A1 + y2 A2 + ¼ A3	=	+ y2 b Y + ¼ c Z	(O-II)	(4b)
  B4	=	+ y2 A1 - y2 A2 + ¾ A3	=	- y2 b Y + ¾ c Z	(O-II)	(4b)
  B5	=	+ (x3 - y3) A1 + (x3 + y3) A3 + z3 A3	=	+ x3 a X + y3 b Y + z3 c Z	(O-III)	(8c)
  B6	=	- (x3 - y3) A1 - (x3 + y3) A3 + (½ + z3) A3	=	- x3 a X - y3 b Y + (½ + z3) c Z	(O-III)	(8c)
  B7	=	- (x3 + y3) A1 - (x3 - y3) A3 + (½ - z3) A3	=	- x3 a X + y3 b Y + (½ - z3) c Z	(O-III)	(8c)
  B8	=	+ (x3 + y3) A1 + (x3 - y3) A3 - z3 A3	=	+ x3 a X - y3 b Y - z3 c Z	(O-III)	(8c)
  B9	=	+ (x4 - y4) A1 + (x4 + y4) A3 + z4 A3	=	+ x4 a X + y4 b Y + z4 c Z	(Si)	(8c)
  B10	=	- (x4 - y4) A1 - (x4 + y4) A3 + (½ + z4) A3	=	- x4 a X - y4 b Y + (½ + z4) c Z	(Si)	(8c)
  B11	=	- (x4 + y4) A1 - (x4 - y4) A3 + (½ - z4) A3	=	- x4 a X + y4 b Y + (½ - z4) c Z	(Si)	(8c)
  B12	=	+ (x4 + y4) A1 + (x4 - y4) A3 - z4 A3	=	+ x4 a X - y4 b Y - z4 c Z	(Si)	(8c)

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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).