Crystal Lattice Structures:	Creation Date:  8 Apr 2002
	Last Modified: 21 Oct 2004

The Ca₇Ge Structure

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.
• visualize the structure (Uses the JMOL Applet)

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• Note that if we replace the Ge atom by a Ca, we get an 8 atom supercell of the A1 (fcc) structure with lattice constant a_fcc = ½ a.
• If, instead, we replace the Ca atom on the (4b) site by a Ge atom, we get a doubled unit cell of the Cu₃Au (L1₂) structure.
• Removing the (4a) atom gives a structure which can be used to calculate the vacancy formation energy in fcc elemental solids.

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• Prototype: Ca₇Ge
• Pearson Symbol: cF32
• Space Group: Fm3m (Cartesian and lattice coordinate listings available)
• Number: 225
• Reference: Pearson's Handbook Vol. IV, p. 2057
• Other Compounds with this Structure: LiPt₇, MoZn₇
• Primitive Vectors:

  A1	=	½ a Y + ½ a Z
  A2	=	½ a X + ½ a Z
  A3	=	½ a X + ½ a Y

• Basis Vectors:

  B1	=		0		(Ge)	(4a)
  B2	=	½ A1 + ½ A2 + ½ A3	=	½ a X + ½ a Y + ½ a Z	(Ca)	(4b)
  B3	=	½ A1	=	¼ a Y + ¼ a Z	(Ca)	(24d)
  B4	=	½ A2	=	¼ a X + ¼ a Z	(Ca)	(24d)
  B5	=	½ A3	=	¼ a X + ¼ a Y	(Ca)	(24d)
  B6	=	- ½ A2 + ½ A3	=	¼ a Y - ¼ a Z	(Ca)	(24d)
  B7	=	- ½ A1 + ½ A3	=	¼ a X - ¼ a Z	(Ca)	(24d)
  B8	=	- ½ A1 + ½ A2	=	¼ a X - ¼ a Y	(Ca)	(24d)

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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).