Systems with Twist=2π
A Band of finite width/height with T=2 is also Chiral- Such a band can have three
C2 axes (D2 point group)
- A journey starting at any arbitrary point on the surface
takes one traversal of the cycle to return to the
starting point
- In the limit, a cycle with zero width/height lies
exclusively in 2D space
© H. S. Rzepa, 2007.