Dietz Joseph D, Hoy Robert S
Department of Physics, University of South Florida, Tampa, Florida 33620, USA.
J Chem Phys. 2022 Jan 7;156(1):014103. doi: 10.1063/5.0072386.
The widely used double-bridging hybrid (DBH) method for equilibrating simulated entangled polymer melts [Auhl et al., J. Chem. Phys. 119, 12718-12728 (2003)] loses its effectiveness as chain stiffness increases into the semiflexible regime because the energy barriers associated with double-bridging Monte Carlo moves become prohibitively high. Here we overcome this issue by combining DBH with the use of core-softened pair potentials. This reduces the energy barriers substantially, allowing us to equilibrate melts with N ≃ 40N and chain stiffnesses all the way up to the isotropic-nematic transition using simulations of no more than 100 × 10 time steps. For semiflexible chains, our method is several times faster than the standard DBH; we exploit this speedup to develop improved expressions for Kremer-Grest melts' chain-stiffness-dependent Kuhn length ℓ and entanglement length N.
广泛用于平衡模拟缠结聚合物熔体的双桥接混合（DBH）方法[Auhl等人，《化学物理杂志》119, 12718 - 12728 (2003)]，随着链刚度增加到半柔性状态而失去有效性，因为与双桥接蒙特卡罗移动相关的能垒变得过高。在这里，我们通过将DBH与使用核软化对势相结合来克服这个问题。这大大降低了能垒，使我们能够使用不超过100×10个时间步长的模拟来平衡具有N≃40N且链刚度一直到各向同性 - 向列相转变的熔体。对于半柔性链，我们的方法比标准DBH快几倍；我们利用这种加速来开发关于Kremer - Grest熔体的链刚度相关的库恩长度ℓ和缠结长度N的改进表达式。
