The wormlike-chain model is commonly used to describe the statistical properties of DNA and liquid-crystal polymers. Following the Green's function approach, here we present the confinement free energy, compression force, and conformational properties of a wormlike chain in slit confinement over a full range of chain lengths (from rodlike, to semiflexible, and to flexible) and confinement widths (from wide to narrow). Some of these properties have previously been covered in the extreme asymptotic limits of polymer chain lengths and slit widths. The current calculation yields the numerical results that navigate the crossover between these extremes and hence provides a comprehensive picture over the entire parameter space for an ideal wormlike chain with no excluded-volume effects.

A key model to support the understanding of the forced extension of real polymers is the wormlike chain under a stretching potential, which is characterized by two basic parameters, the stiffness and the external force. Here, adopting commonly used theoretical and computational approaches, we provide a high-precision numerical solution over a large range of the parameter space. The validity of previous theoretical studies and the current work, for both extension− force relations and the mean square end-to-end distance projected along the direction perpendicular to the stretching, is critically examined using the numerical data as the benchmark.