13 research outputs found
Multilayer approximation for a confined fluid in a slit pore
A simple Lennard-Jones fluid confined in a slit nanopore with hard walls is
studied on the basis of a multilayer structured model. Each layer is
homogeneous and parallel to the walls of the pore. The Helmholtz energy of this
system is constructed following van der Waals-like approximations, with the
advantage that the model geometry permits to obtain analytical expressions for
the integrals involved. Being the multilayer system in thermodynamic
equilibrium, a system of non-linear equations is obtained for the densities and
widths of the layers. A numerical solution of the equations gives the density
profile and the longitudinal pressures. The results are compared with Monte
Carlo simulations and with experimental data for Nitrogen, showing very good
agreement.Comment: 6 pages, 5 figures
Cluster pair correlation function of simple fluids: energetic connectivity criteria
We consider the clustering of Lennard-Jones particles by using an energetic
connectivity criterion proposed long ago by T.L. Hill [J. Chem. Phys. 32, 617
(1955)] for the bond between pairs of particles. The criterion establishes that
two particles are bonded (directly connected) if their relative kinetic energy
is less than minus their relative potential energy. Thus, in general, it
depends on the direction as well as on the magnitude of the velocities and
positions of the particles. An integral equation for the pair connectedness
function, proposed by two of the authors [Phys Rev. E 61, R6067 (2000)], is
solved for this criterion and the results are compared with those obtained from
molecular dynamics simulations and from a connectedness Percus-Yevick like
integral equation for a velocity-averaged version of Hill's energetic
criterion.Comment: 17 pages, 6 figure
Hyperuniformity on spherical surfaces
9 pags., 8 figs., 1 tab., 1 app.We study and characterize local density fluctuations of ordered and disordered hyperuniform point distributions on spherical surfaces. In spite of the extensive literature on disordered hyperuniform systems in Euclidean geometries, to date few works have dealt with the problem of hyperuniformity in curved spaces. Indeed, some systems that display disordered hyperuniformity, like the spatial distribution of photoreceptors in avian retina, actually occur on curved surfaces. Here we will focus on the local particle number variance and its dependence on the size of the sampling window (which we take to be a spherical cap) for regular and uniform point distributions, as well as for equilibrium configurations of fluid particles interacting through Lennard-Jones, dipole-dipole, and charge-charge potentials. We show that the scaling of the local number variance as a function of the window size enables one to characterize hyperuniform and nonhyperuniform point patterns also on spherical surfaces.A.G.M., G.Z., and E.L. acknowledge the support from the European Union’s Horizon
2020 Research and Innovation Programme under the Marie
Skłodowska-Curie Grant No. 734276. E.L. also acknowledges
funding from the Agencia Estatal de Investigación and Fondo
Europeo de Desarrollo Regional (FEDER) under Grant No.
FIS2017-89361-C3-2-P. S.T. was supported in part by the National Science Foundation under Award No. DMR-1714722