Criterion of thermal denaturation for modified-self-consistent-phonon-theory mean-field calculations in DNA polymers

More exact mean-field modified-self-consistent-phonon-theory calculations are shown that give self-consistent solutions at temperatures above those that led to the loss of solution in earlier calculations and above the actual melting temperatures of several DNA polymers. We show that these high-temperature solutions are unphysical and still indicate a softening of the helical system that can be associated with nonsolidlike behavior. The temperatures for the onset of unphysical behavior are very close to the critical temperatures of earlier calculations.