  We suggested a geometric approach to address the external field influence on
the DNA molecules, described by the WLC model via geometric coupling. It
consists in the introduction of the effective metrics depending on the
potential of the external field, with further re-definition of the arc-length
parameter and of the extrinsic curvatures of the DNA molecules. It yields the
nontrivial impact of the external field in the internal energy of
macromolecules. We give the Hamiltonian formulation of this model and perform
its preliminary analysis in the redefinition of the initial energy density.
