The analytical study of a disordered system is usually difficult due to the necessity to perform a quenched average over the disorder. Thus, one may resort to the easier annealed ensemble as an approximation to the quenched system. In the study of RNA secondary structures, we explicitly quantify the deviation of this approximation from the quenched ensemble by looking at the correlations between neighboring bases. This quantified deviation then allows us to propose a constrained annealed ensemble which predicts some physical quantities much closer to the results of the quenched ensemble without becoming technically intractable.

• Received 12 April 2005

DOI:https://doi.org/10.1103/PhysRevE.72.061905