Determination of fluid-solid transitions in model protein solutions using the histogram reweighting method and expanded ensemble simulations

The crystallization of a model protein was analyzed using computer simulation. The model consisted of spheres having both an isotropic interaction of short range and anisotropic interactions between patch-antipatch pairs. Expanded ensemble simulations of the Einstein crystal was used to calculate the free energy of a protein crystal. It was found that at low temperatures, the anisotropic attractions lead to a weak first-order transition between orientationally disordered and ordered face-centered cubic structures.