Nematic Disclinations

Topological defects in liquid crystal orientation field — core energy and winding number

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In nematic liquid crystals, the director field n̂(r) (headless unit vector) can have topological defects called disclinations with half-integer winding numbers s = ±½, ±1. The Frank elastic energy scales as F ~ πKs²ln(R/rc). The +½ and −½ disclinations are topologically stable in nematics (π₁(RP²) = Z₂); they attract and annihilate in pairs. The core energy regularizes the logarithmic divergence. Click the canvas to add a defect.