Another possible source for the small increase in error when testing on longer DNA sequences is that the atomic configurations themselves might not be represented as well by the training set. Recall that the training structures were sampled from the center of a DNA strand (Fig. ). Longer DNA chains might adopt configurations that are more similar to those at the edges of DNA, farther from the training data of only central base pairs used for this model. Again, this could be accounted for by including "edge" base pair configurations in addition to the "center" configurations that are currently in the training set.