Study of unzipping transitions in an adsorbed polymer by a periodic force

Using Monte Carlo simulations, we study the dynamic transitions in the unzipping of an adsorbed homogeneous polymer on a surface (or wall). We consider three different types of surfaces. One end of the polymer is always kept anchored, and other end monomer is subjected to a periodic force with frequency $\omega$ and amplitude $g_0$. We observe that the force-distance isotherms show hysteresis loops in all the three cases. For all the three cases, it is found that the area of the hysteresis loop, $A_{loop}$, scales as $1\mathrm{/}\omega$ in the higher frequency regime, and as $g_0^{\alpha }{\omega }^{\beta }$ with exponents $\alpha =1$ and $\beta =1.25$ in the lower frequency regime. The values of exponents $\alpha$ and $\beta$ are similar to the exponents obtained in the earlier Monte Carlo simulation studies of DNA chains and a Langevin dynamics simulation study of longer DNA chains.