• Helical Phase:
  n(z)= x cos(q z)+y sin(q z)
• Twists in Only One Radial Direction

• Double Twist Tube:
  n(r) = z cos(q r) - theta sin(q r)
• Twists in Both Radial Directions
• Double Twist in Center,
  Single Twist at r = pi/2 q

• 45 degree Tubes Pack at Right Angles
• Defect Lines Thread Right-Handed Corners
• Cubic Blue Phases

• The Blue Phases: Introduction
• What Are Liquid Crystals?
• Order Parameter Fields
• Defects in Nematic Liquids
• Homotopy Theory and Defects
• Parallel Transport and Energy
• Twisted Parallelism: Chiral Nematics
• Chiral Nematic Phases: Helical and Blue
• Blue Phases: Networks of Defect Lines
• Defect Lines and Frustration: Curved Space

Links Back

Sethna's Research 90-94

Entertaining Science done at

LASSP.

James P. Sethna, sethna@lassp.cornell.edu

Statistical Mechanics: Entropy, Order Parameters, and Complexity, now available at Oxford University Press (USA, Europe).