Fig. 2.

MD simulation results. Potentials of mean force W for PS₂₀ as a function of the radius of gyration $R_g$ (A), normalized so that ${\displaystyle {\int }_0^{\infty }\exp \left(-W\left(R_g\right)/k_{B}T\right)d{R}_g}=1$, and along the end-to-end distance L (B), normalized so that ${\displaystyle {\int }_0^{\infty }4\pi L^2\exp \left(-W\left(L\right)/k_{B}T\right)dL}=1$. (C) Force vs. end-to-end distance profile of different LJ polymer in the gas phase using steered MD simulation. We average over the force at the plateau region to compute the unfolding force. (D) Scaling of plateau force with degree of polymerization for the gas-phase LJ chain and the corresponding power law fits. Data are shown for two different pulling rates but, irrespective of the pulling rate, the results are well fitted by a power law of $F=a{N}^b$ with $b=0.27$.