Free energy of a wormlike polymer chain confined in a slit: Crossover between two scaling regimes

We consider a wormlike polymer confined between two flat surfaces separated by a distance W. Using a wormlike chain formalism that couples the orientational and positional degrees of freedom, for a wormlike chain much longer than the persistence length l(p), we calculate the free energy per segment as a function of W and compare it with the two scaling behaviors valid in the large and small W/l(p) limits.