LiO Structure: AB_hP8_194_ac

Prototype	LiO
AFLOW prototype label	AB_hP8_194_ac_f-003
ICSD	25530
Pearson symbol	hP8
Space group number	194
Space group symbol	$P 6_{3} / mm c$
AFLOW prototype command	aflow --proto=AB_hP8_194_ac_f-003 --params= $a, c / a, z_{3}$

(Fehér, 1953) and (Föppl, 1957) presented competing structures for LiO, both in space group $P \overline{6}$ #174. First-principles calculation by (Cota, 2005) and (Chen, 2011) suggest that the Föppl structure is correct, but show that the proper space group is $P 6_{3} / mm c$ #194. This is generally held to be the correct structure, e.g. (Jain, 2013). We use the symmetrization of Föppl's original data made by (Cota, 2005).
The ICSD entry is from Föppl, 1957), updated to make the space group $P 6_{3} / mm c$ .

a_{1} a_{2} a_{3} = = = \frac{1}{2} a \hat{x} - \frac{3}{2} a \hat{y} \frac{1}{2} a \hat{x} + \frac{3}{2} a \hat{y} c \hat{z}

Basis vectors

		Lattice coordinates		Cartesian coordinates	Wyckoff position	Atom type
$B_{1}$	=	$0$	=	$0$	(2a)	Li I
$B_{2}$	=	$\frac{1}{2} a_{3}$	=	$\frac{1}{2} c \hat{z}$	(2a)	Li I
$B_{3}$	=	$\frac{1}{3} a_{1} + \frac{2}{3} a_{2} + \frac{1}{4} a_{3}$	=	$\frac{1}{2} a \hat{x} + \frac{3}{6} a \hat{y} + \frac{1}{4} c \hat{z}$	(2c)	Li II
$B_{4}$	=	$\frac{2}{3} a_{1} + \frac{1}{3} a_{2} + \frac{3}{4} a_{3}$	=	$\frac{1}{2} a \hat{x} - \frac{3}{6} a \hat{y} + \frac{3}{4} c \hat{z}$	(2c)	Li II
$B_{5}$	=	$\frac{1}{3} a_{1} + \frac{2}{3} a_{2} + z_{3} a_{3}$	=	$\frac{1}{2} a \hat{x} + \frac{3}{6} a \hat{y} + c z_{3} \hat{z}$	(4f)	O I
$B_{6}$	=	$\frac{2}{3} a_{1} + \frac{1}{3} a_{2} + (z_{3} + \frac{1}{2}) a_{3}$	=	$\frac{1}{2} a \hat{x} - \frac{3}{6} a \hat{y} + c (z_{3} + \frac{1}{2}) \hat{z}$	(4f)	O I
$B_{7}$	=	$\frac{2}{3} a_{1} + \frac{1}{3} a_{2} - z_{3} a_{3}$	=	$\frac{1}{2} a \hat{x} - \frac{3}{6} a \hat{y} - c z_{3} \hat{z}$	(4f)	O I
$B_{8}$	=	$\frac{1}{3} a_{1} + \frac{2}{3} a_{2} - (z_{3} - \frac{1}{2}) a_{3}$	=	$\frac{1}{2} a \hat{x} + \frac{3}{6} a \hat{y} - c (z_{3} - \frac{1}{2}) \hat{z}$	(4f)	O I

L. G. Cota and P. de la Mora, On the structure of lithium peroxide, Li $_{2}$ O $_{2}$ , Acta Crystallogr. Sect. B 61, 133–136 (2005), doi:10.1107/S0108768105003629.
F. Fehér, I. von Wilucki, and G. Dost, Beiträge zur Kenntnis des Wasserstoffperoxyds und seiner Derivate, VII. Mitteil.: Über die Kristallstruktur des Lithiumperoxyds, Li $_{2}$ O $_{2}$ , Chem. Ber. 86, 1429–1437 (1953), doi:10.1002/cber.19530861111.
H. Föppl, Die Kristallstrukturen der Alkaliperoxyde, Z. Anorganische und Allgemeine Chemie 291, 12–50 (1957), doi:10.1002/zaac.19572910104.
A. Jain, S. Ping, G. Hautier, W. Chen, W. D. Richards, S. Dacek, S. Cholia, D. Gunter, D. Skinner, G. Ceder, and K. A. Persson, Commentary: The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1, 011002 (2013), doi:10.1063/1.4812323.

M. K. Y. Chan, E. L. Shirley, N. K. Karan, M. Balasubramanian, Y. Ren, J. P. Greeley, and T. T. Fister, Structure of Lithium Peroxide, J. Phys. Chem. Lett. 2, 2483–2486 (2011), doi:10.1021/jz201072b.

Encyclopedia of Crystallographic Prototypes