Lecture 6: 3D Lattices, 3D Symmetry, Space Groups
Lecture 6: 3D Lattices, 3D Symmetry, Space Groups
Lecture 6: 3D Lattices, 3D Symmetry, Space Groups
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SPACE GROUPS: : symmetry in space (including translation); the various<br />
ways in which motifs can be arranged in space in a homogeneous array<br />
The space groups are combinations of the 14 possible BRAVAIS<br />
LATTICES with the 32 POINT GROUPS (crystal classes), including<br />
glide planes and screw axe = 230 SPACE GROUPS<br />
It’s s easy to find the point group from the space group designation:<br />
a, b, c, n, d all reduce to “m”<br />
screw axes, like 2 1 , reduce to simple rotation axes, i.e., “2”<br />
Ex.<br />
<strong>Space</strong> group I2/b2/a2/m = Point group 2/m2/m2/m<br />
<strong>Space</strong> group P2 1 /b2 1 /c2 1 /a = Point group 2/m2/m2/m
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