REMARKS ON DISCRETE AND CONTINUOUS LARGE-SCALE MODELS OF DNA DYNAMICS

We present a comparison of the continuous versus discrete models of la rge-scale DNA conformation, focusing on issues of relevance to molecul ar dynamics. Starting from conventional expressions for elastic potent ial energy, we derive elastic dynamic equations in terms of Cartesian coordinates of the helical axis curve, together with a twist function representing the helical or excess twist. It is noted that the convent ional potential energies for the two models are not consistent. In add ition, we derive expressions for random Brownian forcing for the nonli near elastic dynamics and discuss the nature of such forces in a conti nuous system.