  We show that the simple analytical model proposed by Zhang and Marko (Phys.
Rev. E 77, 031916 (2008)) to illustrate Maxwell relations for single-DNA
experiments can be improved by including the zero-force entropy of a Gaussian
chain. The resulting model is in excellent agreement with the discrete
persistent-chain model and is in a form convenient for analyzing experimental
data.

Soft Condensed Matter;Biological Physics