Dynamics of orientationally ordered domains in a short chain-molecule system: Size dependence of domain oscillation Original Research Article

It was reported, in our previous works, that two orientationally ordered domains of short chain molecules move collectively as if they were rigid bodies in spite of the non-bonded short-range interaction potential (Lennard–Jones potential) among chain molecules. In this paper, in order to investigate the rigidity of the domain of short chain molecules in further detail, molecular dynamics simulations are performed for the following four case combinations of domains: the case I, II, III and IV are (61+29), (61+61), (124+61) and (124+124) chain molecule combinations, respectively. From these simulations, the size dependence of the domainsʹ motion is demonstrated. Estimating an oscillation period τ for each case, it is found that τ(61,29)≃τ(61,61)<τ(124,61)<τ(124,124). This relation is a peculiar property of orientationally ordered domains in a short chain-molecule system.