Effects of chain flexibility on the conformational behavior of a single polymer chain

摘要

Effects of chain flexibility on conformational behavior as a function of temperature have been investigated by coarse-grained molecular dynamics (MD) simulation. The paper presents simulation results regarding the potential energies and structural parameters of a single polymer chain made of 100, 200, or 300 beads with various chain flexibilities. Our simulations exhibit the conformational transition from a random coil to a folded structure demonstrated by the curves of non-bonded po(t)ential energy, bond-orientational order parameters and characteristic ratios of real polymer chains with a cooling temperature. In this paper, the comparison between the real polymer chain model involving non-bonded interaction and the ideal polymer chain model in the absence of long-range interaction has also been made. It shows that the main factor inducing structural transition lies in the non-bonded interaction. This result explains clearly that the long-range interaction plays an important role in the polymer folding process. Moreover, the flexibility, as well as the chain length of a real polymer chain, strongly effects on its transition temperature. It also concludes that the changes of bond-torsional potential energy and characteristic ratio with the reduced temperature in the ideal polymer models are independent of chain length, but present different tendencies according to the chain flexibility.