Effect of elastic degrees of freedom at columnar-crystalline phase transition

2014 A Ginzburg-Landau Hamiltonian describing systems of disc-like molecules in the columnar phase is used to investigate the properties of the columnar-crystalline transition. Near the transition temperature in the columnar phase, the enhancement of the bend elastic constant is found by a perturbation calculation. The gauge coupling mechanism which leads to a first order transition in the case of the superconductor or nematic-smectic-A transition is found to leave the transition continuous here. A coupling of the form found in compressible magnets may lead to a first order transition for large coupling. Our results are briefly compared with those of Kats. J. Physique 45 (1984) 1039-1048 JUIN 1984, Classification Physics Abstracts 64.70M