Figure 5.

Simulated ground states of discrete-filament model of chiral bundles at fixed N = 181, for increasing values of reduced twist Ωd, where d is equilibrium centre-to-centre filament spacing, or diameter. Top row shows a relatively ductile case where cohesive interaction range σ is equal to d, showing a transition from (approximately) cylindrical defect-free bundles to defective, cylindrical packings possessing excess fivefold disclinations, i.e. Q = +1, +2 and +3. Red (blue) filaments label sites of interior fivefold (sevenfold) disclinations. The bottom row shows a relatively ductile case, where low-twist, defect-free cylinders transition to intermediate-twist anistropic ‘tape-like’ bundles, followed by a re-entrant cylindrical morphology (with excess defects) at high twist.