We investigated the statistical behaviors of semiflexible polymer chains, which were simultaneously subjected to force stretching and rectangular tube confinement. Based on the wormlike chain model and Odijk deflection theory, we derived a new deflection length, by using which new compact formulas were obtained for the confinement free energy and force⁻confinement⁻extension relations. These newly derived formulas were justified by numerical solutions of the eigenvalue problem associated with the Fokker⁻Planck governing equation and extensive Brownian dynamics simulations based on the so-called generalized bead-rod (GBR) model. We found that, compared to classical deflection theory, these new formulas were valid for a much more extended range of the confinement size/persistence length ratio and had no adjustable fitting parameters for sufficiently long semiflexible chains in the whole deflection regime.
Keywords: Brownian dynamics simulation; GBR model; Odijk length; rectangular tube confinement; slit confinement; stretch; wormlike chain model.