局所秩序変数を用いた多段核生成現象の解析

抄録

  Multistep nucleation can be broadly classified into several types, in each of which the occurrence of precursor phenomenon is observed. However, the true nature and role of the precursor phenomenon are controversial. In this report, molecular dynamics simulations are performed for the nematic (N) to smectic (Sm) phase transition of uniaxial liquid crystals induced by supercooling. In the N-Sm transition, a precursor phenomenon, known experimentally as “pre-transition fluctuation,” in which the X-ray diffraction intensity increases at temperatures higher than the phase transition temperature, has been believed to be the generation of molecular clusters with Sm-like short-range order, although no direct evidence exists. To visualize the pre-transition fluctuation, appropriate local order parameters are introduced by applying machine learning. The development of the N-Sm transition through multistep nucleation is demonstrated, suggesting the true nature and role of pre-transition fluctuation.