  We investigate kinetic pathways of the DNA melting transition using
variable-range versions of the Poland-Scheraga (PS) and Peyrard-Dauxois-Bishop
(PDB) models of DNA. In the PS model, we construct a phi^4-field theory to
calculate the critical droplet profile, the initial growth modes, and the
exponent characterizing the divergence of the susceptibility near the spinodal.
In the PDB model, we use a mean field analysis to calculate susceptibility
exponent. We compare these theoretical results with Monte Carlo and Brownian
dynamic simulations on the PS and PDB models, respectively. We find that by
increasing the range of interaction, the system can be brought close to a
pseudospinodal, and that in this region the nucleating droplet is diffuse in
contrast to the compact droplets predicted by classical nucleation theory.
