Multipoint Segmental Repulsive Potential Model for Dissipative Particles Dynamics of Uncrossing Polymer Chains

In scientific and industrial fields, dissipative particle dynamics (DPD) simulation is a widely used coarse-grained molecular dynamics for studying the structural and thermodynamic properties of polymeric systems. A long-standing problem in DPD polymers is that unphysical bond crossings are caused due to utilization of soft-core potential. This means that the standard DPD cannot capture entanglement effects that play a crucial role in mechanical properties of long polymers. To overcome such a drawback, a segmental repulsive potential (SRP) model has been developed by several groups. In the SRP models, repulsive potential between bonds is added to the DPD polymer as a function of the distance between nearest points or midpoints on each bond. The SRP models have been shown that bond crossings are effectively reduced and reptation-like behaviors are successfully reproduced. However, cut-off radius of the SRP $d_{\rm c}$ (thickness of bonds) is too large to maintain static properties of the standard DPD polymer. In the present study, for reducing $d_{\rm c}$ and artificial effects in SRP models, we propose a modification of the SRP model by using multipoint cites (mp-SRP) instead of single cite for bond-bond interactions.