8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Thu 811:10-14:00P7.87On the scaling of molecular dynamics andSmoluchowski-Fokker-Planck survival times ofanisotropic fluidsWilmer Olivares-Rivas 1 and Pedro J. Colmenares 11 Universidad de Los Andes, Grupo de Química Teórica QUIFFIS, Dpto. Química,Facultad de Ciencias, La Hechicera 5101, Mérida, VenezuelaOn a previous work [Phys. Rev. E, 80, 061123 (2009)], we presented an approximated analyticalsolution for the Langevin equation of an anisotropic fluid, which allowed the evaluation of theposition dependent diffusion coefficient, from the virtual layer Molecular Dynamics data. Sincethe time scale of the Langevin Dynamics and Molecular Dynamics are different, an anzat forthe persistence or survival probability relaxation time was needed. In this work we solve theSmoluchowski-Fokker-Planck equation for a Lennard-Jones dense fluid next to an attractive wall,and show how the Langevin Dynamics mean first passage time, averaged over the local particledensity in consecutive layers of the fluid, scales with the corresponding Molecular Dynamicsquantity. The density average of the mean first passage time over the initial positions z o of a layerlocated at z a, lt; t MFP (z 0 ) > a, is equivalent to the persistence or survival relaxation time τ(z a ). Our scaled Langevin Dynamics persistence time, τ LD (z a ), evaluated in terms of simpleintegrals over the equilibrium local density, gives a good match with that obtained from the virtuallayer Molecular Dynamics method τ MD (z a ).87