Sixfold Screw Axes (6n)
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The symbols above show sixfold screw axes perpendicular to the
plane of the screen, i.e parallel to Z.
A sixfold screw axis is equivalent to an anticlockwise rotation of 60°
about a line followed by a translation parallel to that line.
The translation is either 1/6, 1/3, 1/2, 2/3, or 5/6 of the repeat distance
in the lattice along the axis for six-one, six-two, six-three, six-four, and
six-five screw axes, respectively.
A six-one screw axis with
a sixfold rotation about the c-axis, i.e. about
the line 0,0,z, followed by a translation of 1/6 c
along it, will have
the corresponding symmetry operator x-y,x,1/6+z.
Note that six-one and six-five are equivalent
except for handedness (right- and left-handed, respectively) as
are six-two and six-four screw axes,
in contrast to the six-three axis, which has no handedness.
These axes have the written symbols "61",
"62",
"63",
"64", and
"65", respectively.
© Copyright 1997-1999.
Birkbeck College, University of London.