Eur. Phys. J. E 4, 305-313
Overlap distribution in random and designed heteropolymers
U. BastollaMax Planck Institut for Colloids and Interfaces, D-14424 Potsdam, Germany HLRZ, Forschungszentrum Jülich, D-52425 Jülich, Germany bastolla@mpikg-golm.mpg.de
ugo@chemie.fu-berlin.de
(Received 16 August 2000)
Abstract
We study the overlap between low-energy states in lattice models of
heteropolymers with contact interactions.
The overlap distribution gives information on the degree of correlation
in the energy landscape.
Designed sequences have rather correlated energy landscapes, which
favor fast folding kinetics.
Chains with random interactions have much less correlated energy landscapes.
It is indeed believed that the mean-field theory for this model coincides
with the Random Energy Model, whose different low-energy states are
completely unrelated.
This picture has been supported by numerical studies of maximally compact
configurations. Without applying this constraint, we find that
the overlap distribution is indeed bimodal as expected, but it
has a broad peak at large overlap, indicating a non-vanishing width for
the valleys of low-energy states.
This feature probably plays an
important role in the kinetics of the model. It is not evident that the range
of such correlations shrinks to zero for large systems.
The range of the correlations seems to be influenced by the number of
contacts per residue in the ground state: the smaller this quantity, the
larger the correlations.
87.15.Aa - Biomolecules: theory and modeling; computer simulation.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001
