Origin at -1 on glide plane b

Asymmetric unit

0 ≤ x ≤ 1; 0 ≤ y ≤ 1/2; 0 ≤ z

(1)  1

(2)  2   x, 1/4, 0

(3)  -1   0, 0, 0

(4)  b   0, y, z

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

Positions

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

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

Symmetry of special projections

Along [001]   p2mg a' = bp   b' = -a    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] pb11 (12)	1; 4
	[2] p211 (8)	1; 2
	[2] p-1 (2)	1; 3

IIa

none

IIb	[2] p21/b11 (a' = 2a) (17)

Maximal isotypic subgroups of lowest index

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IIc	[2] p2/b11 (a' = 2a) (16)

Minimal non-isotypic supergroups

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I	[2] pmaa (38); [2] pban (39); [2] pmam (40); [2] pbaa (43)

II	[2] c2/m11 (18); [2] p2/m11 (b' = 1/2b) (14)

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