Title: Surface tension at the liquid-vapor interface of screened ionic mixtures
Authors: M.González-Melchor (Depto. de Física, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 México D.F., México) , C.Tapia-Medina (Depto. de Energía, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa, 02200 México D.F., México) , L.Mier-y-Ter\'an (Depto. de Física, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 México D.F., México) , J.Alejandre (Depto. de Química. Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 México D.F., México)

The liquid-vapor interface of binary mixtures of charged particles is studied using molecular dynamics (MD) simulations. The interaction between particles is given by a short-range repulsive potential plus an attractive/repulsive Yukawa term, which models screened electrostatic interactions. To obtain the components of the pressure tensor two methods were used: a hybrid MD method which combines the hard sphere and continuous forces and a standard continuous MD method where the hard sphere was replaced by a soft interaction. We show that both models give essentially the same results. As the range of interaction decreases, the critical temperature and surface tension increase. The comparison with the restricted primitive model of ionic fluids is discussed.

Key words: ionic fluids, molecular simulation, surface tension, liquid-vapor
PACS: 61.20.Gy, 61.20.Ja, 64.70.Dv