Pca21 jpeg

International Tables for Crystallography (2006). Vol. A, Space group 29, pp. 226-227,

Pca 2i

No. 29

r⁵

Pca2_l

mml    Orthorhombic

Patterson symmetry Pmmm

Pb2_xa

Origin on 1 £*2, Asymmetric unit 0 Symmetry operations

(1) 1 (2) 2(0,0,

	Ł		£	1
?	ł		!
i )	1		i	o			—
i	i		i
J	f		f
	P2,ca \		t
				1*0		!*0
					o*		O*
					OJ*		Ol*
				*0		*o
				i*o		i*o
\			i		o*		o*
x< i;	0 <y < 1;		0 <z < 1
0,0,z		(3)	x,0,z	(4) c j,y,z

CONTINUED

No. 29

Pca 2

Generatora selected (1).; r(l ,0,0); *(0,1,0); *(0,0,1); (2); (3)

Positions Multiplicity, Wyckoffletter, Site symmetry		Coordinates		Reflection conditions General:
4 a 1	(1 )x,y,z	(2)x,y,z-f-i (3)x + i,y,z	(4)x+i,y,z + {	Oki: 1 = 2 n hOl : h = 2n hOO: h = 2n 001: l = 2n

Maximal non-isomorphic subgroups

I	(2]Plai(Pc,7) 1;	3
	[2]Pcll(Pc,7) 1;	4
	[2] PI 12, (P2,, 4) 1;	2
na	nonę
Ilb	[2] Pna2t (b' = 2b) (33)

Maximal isomorphic subgroups of lowest index

lic    [2] Pca 2, (b' = 2b) (29); [3] Pca 2, (a’ = 3a) (29); [3] Pca2, (c* = 3c) (29)

Minimal non-isomorphic supergroups

I    [2] Pcca (54); [2] Pbcm (57); [2] Pbcn (60); {2] Pb ca (61)

n    [2] Ccm2, (Cmc2,, 36); [2] Bme2(A em2, 39); [2] Aea2 (41); [2] !ba2 (45); [2] Pcm2, (a' = ±a) (Pmc2„ 26);

[2] Pma2 (c' = ^c) (28)

Symmetry of special projections

Along [001] p2mg a' = a    b' = b

Origin at0,0,z

Ałong (100] plml a' = b b' = 5C Origin at 0,0

Along [010] p 11 g a' = c b = ;a

Origin at 0,y, 0

227