title: Comment on "General equilibrium shape equations of polymer chains".
abstract: In this Comment, we point out that the Euler-Lagrange equations, which are referred to as the general equilibrium shape equations presented by Zhang et al. [Phys. Rev. E 70, 051902 (2004)] are incorrect, along with equations derived from them. The correct equations are provided here and they are cross-checked using certain energy functions previously presented in the literature. Further, with the use of the correct equations, we present new numerical results, which for the values of the constants given by Zhang et al. do not give rise to the physical behavior observed for DNA by those authors. However, the correct equations can be consistent with sensible behavior for different values of the constants.
authors.affiliation: Nanomechanics Group, School of Mathematics and Applied Statistics, University of Wollongong, Wollongong, New South Wales 2522, Australia.
authors.forename: Ngamta
authors.initials: N
authors.lastname: Thamwattana
authors.forename: James M
authors.initials: JM
authors.lastname: Hill