Crystal Lattice Structures:	Creation Date: 14 Dec 1998
	Last Modified: 14 Aug 2006

The αSm Structure (C19)

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)

---

• This is also the ground state structure for Lithium proposed by A. W. Overhauser in Phys. Rev. Lett. 53 64-65 (1984). This is a close-packed structure with stacking ABCBCACAB..., as opposed to ABCABC... in the fcc (A1) structure and ABABAB... in the hcp (A3) structure. In the ``ideal'' case, c = 9 (2/3)^½ a, z = 2/9, and each atom has twelve neighbors a distance `a' away. The atoms on the (1a) site see an fcc-like arrangement of nearest neighbors, while the atoms on the (2c) sites see an hcp-like arrangement.
• 14 Aug 2006: Removed the link to the graphical representation of the Primitive and Basis vectors, as it had a misprint.

---

• Prototype: αSm
• Pearson Symbol: hR3
• Strukturbericht Designation: C19
• Space Group: R3m (Cartesian and lattice coordinate listings available)
• Number: 166
• Other Elements and Compounds with this Structure: Li, Nd₂Tm, NbS₂
• Primitive Vectors:

  A1	=	½ a X - 12-½ a Y + 1/3 c Z
  A2	=	3-½ a Y + 1/3 c Z
  A3	=	- ½ a X - 12-½ a Y + 1/3 c Z

• Basis Vectors:

  B1	=	0			(Sm-I)	(1a)
  B2	=	+ z (A1 + A2 + A3)	=	+ z c Z	(Sm-II)	(2c)
  B3	=	- z (A1 + A2 + A3)	=	- z c Z	(Sm-II)	(2c)

---

Go back to the Lanthanides & Actinides page.

Go back to the hexagonal close-packed and related structures page.

Go back to Crystal Lattice Structure page.

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).