title: Janus fluid with fixed patch orientations: theory and simulations.
abstract: We study thermophysical properties of a Janus fluid with constrained orientations, using analytical techniques and numerical simulations. The Janus character is modeled by means of a Kern-Frenkel potential where each sphere has one hemisphere of square-well and the other of hard-sphere character. The orientational constraint is enforced by assuming that each hemisphere can only point either North or South with equal probability. The analytical approach hinges on a mapping of the above Janus fluid onto a binary mixture interacting via a "quasi" isotropic potential. The anisotropic nature of the original Kern-Frenkel potential is reflected by the asymmetry in the interactions occurring between the unlike components of the mixture. A rational-function approximation extending the corresponding symmetric case is obtained in the sticky limit, where the square-well becomes infinitely narrow and deep, and allows a fully analytical approach. Notwithstanding the rather drastic approximations in the analytical theory, this is shown to provide a rather precise estimate of the structural and thermodynamical properties of the original Janus fluid.
authors.affiliation: Departamento de Física, Universidad de Extremadura, E-06071 Badajoz, Spain. maestre@unex.es
authors.forename: Miguel Ángel G
authors.initials: MÁ
authors.lastname: Maestre
authors.forename: Riccardo
authors.initials: R
authors.lastname: Fantoni
authors.forename: Achille
authors.initials: A
authors.lastname: Giacometti
authors.forename: Andrés
authors.initials: A
authors.lastname: Santos