Origin at centre (2/m)

Asymmetric unit

0 ≤ x ≤ 1/4; 0 ≤ y ≤ 1/2

For (0, 0, 0)+ set

(1)  1

(2)  2   x, 0, 0

(3)  -1   0, 0, 0

(4)  m   0, y, z

For (1/2, 1/2, 0)+ set

(1)  t(1/2, 1/2, 0)

(2)  2(1/2, 0, 0)   x, 1/4, 0

(3)  -1   1/4, 1/4, 0

(4)  b   1/4, y, z

Generators selected (1); t(1, 0, 0); t(0, 1, 0); t(1/2, 1/2, 0); (2); (3)

Positions

Multiplicity, Wyckoff letter, Site symmetry	Coordinates	Reflection conditions
	(0, 0, 0)+  (1/2, 1/2, 0)+	General:
8 f 1	(1) x, y, z (2) x, -y, -z (3) -x, -y, -z (4) -x, y, z	hk: h + k = 2n h0: h = 2n 0k: k = 2n

		Special: as above, plus
4 e  m	0, y, z 0, -y, -z	no extra conditions
4 d  2	x, 0, 0 -x, 0, 0	no extra conditions
4 c  -1	1/4, 1/4, 0 1/4, 3/4, 0	hk: k = 2n
2 b  2/m	1/2, 0, 0	no extra conditions
2 a  2/m	0, 0, 0	no extra conditions

Symmetry of special projections

Along [001]   c2mm a' = a   b' = bp    Origin at 0, 0, z

Along [100]   211 a' = 1/2b    Origin at x, 0, 0

Along [010]   2mm a' = 1/2a    Origin at 0, y, 0

Maximal non-isotypic subgroups

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I	[2] cm11 (13)	(1; 4)+
	[2] c211 (10)	(1; 2)+
	[2] c-1 (p-1, 2)	(1; 3)+

IIa	[2] p21/b11 (17)	1; 3; (2; 4) + (1/2, 1/2, 0)
	[2] p2/b11 (16)	1; 2; (3; 4) + (1/2, 1/2, 0)
	[2] p21/m11 (15)	1; 4; (2; 3) + (1/2, 1/2, 0)
	[2] p2/m11 (14)	1; 2; 3; 4

IIb

none

Maximal isotypic subgroups of lowest index

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IIc	[3] c2/m11 (a' = 3a) (18)

Minimal non-isotypic supergroups

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I	[2] cmmm (47); [2] cmme (48); [3] p-31m (71); [3] p-3m1 (72)

II	[2] p2/m11 (a' = 1/2a, b' = 1/2b) (14)

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