  Reflection of two strongly interacting bosons with long-rage interaction
hopping on a one-dimensional lattice scattered off by a potential step is
theoretically investigated in the framework of the extended Hubbard model. The
analysis shows that, in the presence of unbalanced on-site and nearest-neighbor
site interaction, two strongly correlated bosons forming a bound particle state
can penetrate a high barrier, despite the single particle can not. Such a
phenomenon is analogous to one-dimensional Klein tunneling of a relativistic
massive Dirac particle across a potential step.
