A strength disclination sits in a nematic film with Frank constant (one-constant…

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Order, broken symmetry and collective behaviour · Soft condensed matter

Soft Matter at the Thermal Scale, Ch Frank elasticity, defects and smectic layers

Problem

A strength s=+1s = +1 disclination sits in a nematic film with Frank constant K=8.0 pNK = 8.0\,\mathrm{pN} (one-constant approximation). The defect core has radius rc=5.0 nmr_c = 5.0\,\mathrm{nm} and the sample extends to R=2.0 μmR = 2.0\,\mu\mathrm{m} from the core. ((a)) Calculate the line energy per unit length E/L=πKs2ln⁡(R/rc)E/L = \pi Ks^2\ln(R/r_c). ((b)) Express this as an energy per micrometre of line, in multiples of kBTk_BT at T=298 KT = 298\,\mathrm{K}.

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