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Non-equilibrium molecular dynamics(NEMD)simulations have been performed to study the molecular mechanism of flow-induced crystallization(FIC)of polyethylene(PE).End-to-end distance of chain Rete and the content of trans conformation Ctrans are extracted out to represent intra-chain conformation ordering at whole chain and segment levels,respectively,while orientation correlation function P,density ρ,and bond orientation order parameter are taken to depict inter-chain order.Imposing extension induces intra-chain conformational ordering occurs first,which further couples with inter-chain order and results in the formation of hexagonal packing.Further increasing strain leads to the appearance of orthorhombic order.The results demonstrate that FIC of PE proceed via a multi-stage ordering process,during which coupling among stress,intra-chain conformation,and inter-chain orientation and density orderings.Analyzing on flow-induced energy evolution unveils that not only entropy but also energy play an important role in FIC.