The effect of internal and global modes on the radial distribution function of confined semiflexible polymers

The constraints imposed by nano- and microscale confinement on the
conformational degrees of freedom of thermally fluctuating
biopolymers are utilized in contemporary nano-devices to
specifically elongate and manipulate single chains. A thorough
theoretical understanding and quantification of the statistical
conformations of confined polymer chains is thus a central concern
in polymer physics. We present an analytical calculation of the
radial distribution function of harmonically confined semiflexible
polymers in the weakly bending limit. Special emphasis has been put
on a proper treatment of global modes, i.e. the possibility of the
chain to perform global movements within the channel. We show that
the effect of these global modes significantly impacts the chain
statistics in cases of weak and intermediate confinement. Comparing
our analytical model to numerical data from Monte Carlo simulations
we find excellent agreement over a broad range of parameters