Correspondence relation with respect to entanglement among different simulation models: comparison between bead-spring and bond fluctuation model

Abstract

A novel index for comparing different simulation model polymers with respect to entanglement is proposed. It is the number of elements Ne∗ of ring polymers whose average number of entanglement per molecule is unity; Ne∗ can be calculated with a small-scale computer simulation. We also proposed a method to equilibrate the entangled ring polymers. As an example we calculated Ne∗ with a molecular dynamics simulation using a bead-spring (BS) model which is equivalent to the model proposed by Kremer and Grest [J Chem Phys 92 (1990) 5057], and with a Monte Carlo simulation using bond fluctuation (BF) model. We obtained Ne∗=82±1 for BS model with volume fraction φ=0.43 and Ne∗=59±1 for BF model with φ=0.5. By comparing with the recent result of our group, Ne=89 for BF model with φ=0.5, we can assume that Ne≃1.5Ne∗. If this assumption holds for BS model, its Ne is estimated to be 120, which is 3.4 times greater than the estimated value by Kremer and Grest. The origin of this difference is discussed.