Pmm2 jpeg

International Tabies for Crystallography (2006). Vol. A, Space group 25, pp. 218-219.

Pmm 2 Cl

mml    Orthorhombic

No. 25

Pmml

Patterson symmetry Pmmm

Plmm

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6

's

o.

o*
o*

*o o⁺

*o

•0

*o o*

*o o*

\    \ I

Origin on mml

; 0<y<i; 0<z < 1

(3) m x,0,z    (4) m 0,y,z

Asymmetric unit 0 < x < f Symmetry operations

(1) 1    (2) 2 0,0, z

CONTINUED

No. 25

Pmm 2

Generators selected (1); f(l,0,0); *(0,1,0); *(0,0,1); (2); (3)

Positions

Multiplicity, Wyckoff letter, Site symmetry

4	i	1	(1) x,y,z
2	h	m..	\,y,z
2	8	m..	0,y,z
2	f	. m.	x,i,z
2	e	. m.	x,0 ,z
1	d	mml
1	c	mml	1,0,Z
1	b	mml	0,1,z
1	a	mml	0,0, z

Coordinates

(2 )xj,z    (3) x,y,z

3

0 ,y,z

X, 5,z

x,0,z

(4 )x,y,z

Refiection conditions

General: no conditions

Special: no extra conditions

Symmetry of special projections

Along [001] p2mm a' = a b' = b Origin at0,0,z

Along [100] plm 1 a' = b b' = c Origin at £,0,0

Along [010] pl lm a' = c b' = a

Origin at0,y,0

Maximal non-isomorphic subgroups

I [2JPlml(Pm, 6)    1; 3

[2] Pm 11 (Pm, 6)    1; 4

[2]P112(P2, 3)    1; 2

Ila nonę

nb [2] Pmal (a' = 2a) (28); [2] P&m2 (b' = 2b) {Pmal, 28); [2] Pcc2 (c' = 2c) (27); [2] Pmc2, (c' = 2c) (26);

[2] Pcm2_{ (c' = 2c) (Pmcl,, 26); [2] Aeml (b' = 2b,c' = 2c) (39); [2] Amm2 (b' = 2b,d = 2c) (38);

[2] Bme2 (a' = 2a,c' = 2e) (Aem2,39); [2] Bmm2 (a' = 2a, c' = 2c) (Amm2,38); [2] Cmm2 (a' = 2a, b' = 2b) (35); [2] F mm2 (a' = 2a, b' = 2b, c' - 2c) (42)

Maximal isomorphic subgroups of lowest index

He [2] Pmm2 (a¹ = 2a or b' = 2b) (25); [2] Pmm 2 (c' = 2c) (25)

Minimal non-isomorphic supergroups

X    [2] Pm mm (47); [2] Pmma (51); [2] Pm mn (59); [2}P4mm(99); [2] P4, mc (105); [2]P4m2<115)

n    [2] Cmml (35); [2] Amm 2 (38); [2] Bmm2(Amm2, 38); [2]/mm2 (44)

219