In this animation a model protein consisting of 56 neutral hydrophobic monomers (gray spheres) and 44 charged hydrophilic
monomers (green spheres) is simulated. As a first approximation, all 44 polymer charges (shown as red spheres) are
assumed to have the same (nominal) negative sign and same magnitude. Positive and negative ions in solution are
represented by blue and pink spheres. The density of ions is sustained by a grand canonical Monte Carlo, which causes
ions to be added or removed from the simulation box based on the chemical potential. During the initial part of the
animation only enough ions to neutralize the polymer are present and their number is kept fixed. In the second half of
the animation the grand canonical routine is turned on and the density of ions equilibrates to a predetermined value.
(14 Mb animated gif file)