  We present a nonlinear dynamical model for DNA thermal denaturation, which is
based on the finite stacking enthalpies used in thermodynamical
nearest-neighbour calculations. Within this model, the finiteness of stacking
enthalpies is shown to be responsible for the sharpness of calculated melting
curves. Transfer-integral and molecular dynamics calculations are performed to
demonstrate that the proposed model leads to good agreement with known
experimental results for both homogeneous and inhomogeneous DNA.
