%0 Book Section %1 statphys23_0585 %A Ivanov, V.A. %A Stukan, M.R. %A Spirin, L.A. %A An, E.A. %A Mueller, M. %A Paul, W. %A Binder, K. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K computer effects isotropic-nematic montecarlo polymers semi-flexible simulation solutions statphys23 surface topic-7 transition %T Osmotic equation of state for solutions of semi-flexible macromolecules: Monte Carlo computer simulation %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=585 %X We present results of lattice Monte Carlo computer simulations of solutions of semi-flexible macromolecules using the bond fluctuation model. We have studied athermal solutions of short macromolecules (chain length N=20) with various choices for the chain stiffness in the concentration range from very dilute to concentrated solutions where the appearance of nematic phase becomes possible. Simulations were performed both in canonical and grand canonical ensemble, and we used the configurational bias Monte Carlo algorithm in the latter case. Three techniques to obtain the osmotic equation of state in Monte Carlo simulations are applied and compared in order to critically assess their efficiency and accuracy: the ``repulsive wall'' method, the thermodynamic integration method (which rests on the feasibility of simulations in the grand canonical ensemble), and the recently advocated sedimentation equilibrium method, which records the density profile in an external (e.g. gravitation-like) field and infers, via a local density approximation, the equation of state from the hydrostatic equilibrium condition. We confirm the conclusion that the latter technique is far more efficient than the repulsive wall method, but we find that the thermodynamic integration method is similarly efficient as the sedimentation equilibrium method, and seems to work better for very stiff chains (where the onset of nematic order and the formation of isotropic--nematic interfaces renders the use of the sedimentation equilibrium method problematic at large densities). The effect of a nematic wetting layer at a surface is also discussed.

@incollection{statphys23_0585, abstract = {We present results of lattice Monte Carlo computer simulations of solutions of semi-flexible macromolecules using the bond fluctuation model. We have studied athermal solutions of short macromolecules (chain length N=20) with various choices for the chain stiffness in the concentration range from very dilute to concentrated solutions where the appearance of nematic phase becomes possible. Simulations were performed both in canonical and grand canonical ensemble, and we used the configurational bias Monte Carlo algorithm in the latter case. Three techniques to obtain the osmotic equation of state in Monte Carlo simulations are applied and compared in order to critically assess their efficiency and accuracy: the ``repulsive wall'' method, the thermodynamic integration method (which rests on the feasibility of simulations in the grand canonical ensemble), and the recently advocated sedimentation equilibrium method, which records the density profile in an external (e.g. gravitation-like) field and infers, via a local density approximation, the equation of state from the hydrostatic equilibrium condition. We confirm the conclusion that the latter technique is far more efficient than the repulsive wall method, but we find that the thermodynamic integration method is similarly efficient as the sedimentation equilibrium method, and seems to work better for very stiff chains (where the onset of nematic order and the formation of isotropic--nematic interfaces renders the use of the sedimentation equilibrium method problematic at large densities). The effect of a nematic wetting layer at a surface is also discussed.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Ivanov, V.A. and Stukan, M.R. and Spirin, L.A. and An, E.A. and Mueller, M. and Paul, W. and Binder, K.}, biburl = {https://www.bibsonomy.org/bibtex/298b2543bebd2177232ef2b970f416a8f/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {16418e5fd3bd7540f571305cda555827}, intrahash = {98b2543bebd2177232ef2b970f416a8f}, keywords = {computer effects isotropic-nematic montecarlo polymers semi-flexible simulation solutions statphys23 surface topic-7 transition}, month = {9-13 July}, timestamp = {2007-06-20T10:16:24.000+0200}, title = {Osmotic equation of state for solutions of semi-flexible macromolecules: Monte Carlo computer simulation}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=585}, year = 2007 }