Semi-flexible compact polymers on fractal lattices

Semi-flexible compact polymers modeled by Hamiltonian walks with bending rigidity are studied on 3 and 4-simplex fractal lattices. Hamiltonian walks are weighted according to the number of bends in the walk, and total weights are obtained by an exact recursive treatment. Asymptotic form of the partition function, with temperature dependent scaling parameters, as well as the corresponding critical exponents, is determined. Various thermodynamic quantities are calculated numerically and presented graphically, and the possibility of phase transition between a compact molten globule and an ordered 'crystal' state is investigated. No phase transition is found on either of these two lattices, meaning that fractal geometry here prevents any kind of orientational order. (C) 2011 Elsevier B.V. All rights reserved.