Mechanical denaturation of DNA: existence of a low-temperature denaturation

Recent theoretical predictions on DNA (deoxyribonucleic acid) mechanical separation induced by pulling forces are numerically tested within a model in which self-avoidance for DNA strands is fully taken into account. DNA strands are described by interacting pairs of self-avoiding walks which are pulled apart by a force applied at the two extremities. The whole phase diagram is spanned by extensive Monte Carlo simulations and the existence of a low-temperature denaturation is confirmed. The basic features of the phase diagram and the re-entrant phase boundary are also obtained with a simple heuristic argument based on an energy-entropy estimate.