472 research outputs found
Monte Carlo simulations of the HP model (the "Ising model" of protein folding)
Using Wang-Landau sampling with suitable Monte Carlo trial moves (pull moves
and bond-rebridging moves combined) we have determined the density of states
and thermodynamic properties for a short sequence of the HP protein model. For
free chains these proteins are known to first undergo a collapse "transition"
to a globule state followed by a second "transition" into a native state. When
placed in the proximity of an attractive surface, there is a competition
between surface adsorption and folding that leads to an intriguing sequence of
"transitions". These transitions depend upon the relative interaction strengths
and are largely inaccessible to "standard" Monte Carlo methods.Comment: 6 pages, 6 figures. Article in press. To be published in Computer
Physics Communications (2011
Nuclear vorticity and the low-energy nuclear response - Towards the neutron drip line
The transition density and current provide valuable insight into the nature
of nuclear vibrations. Nuclear vorticity is a quantity related to the
transverse transition current. In this work, we study the evolution of the
strength distribution, related to density fluctuations, and the vorticity
strength distribution, as the neutron drip line is approached. Our results on
the isoscalar, natural-parity multipole response of Ni isotopes, obtained by
using a self-consistent Skyrme-Hartree-Fock + Continuum RPA model, indicate
that, close to the drip line, the low-energy response is dominated by L>1
vortical transitions.Comment: 8 pages, incl. 4 figures; to appear in Phys.Lett.
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