  The translocation time of a polymer chain through an interaction energy
gradient nanopore was studied by Monte Carlo simulations and the Fokker-Planck
equation with double-absorbing boundary conditions. Both the simulation and
calculation revealed three different behaviors for polymer translocation. These
behaviors can be explained qualitatively from free-energy landscapes obtained
for polymer translocation at different parameters. Results show that the
translocation time of a polymer chain through a nanopore can be tuned by
suitably designing the interaction energy gradient.
