Surface tension of fully flexible Lennard-Jones chains: Role of long-range corrections

Abstract

We have calculated the interfacial properties of fully flexible chains formed from tangentially bonded Lennard-Jones beads by direct coexistence. The full long-range tails of the potential are accounted for by means of inhomogeneous long-range corrections consisting in slice by slice summation of interactions away from the truncation sphere. We show that the corrections may be transformed into an effective long-range pair potential plus a self term, thus allowing for a fast and easy implementation of the method. After addition of the effective pair potential, the coexistence densities agree very well with results from Gibbs-ensemble simulations with usual homogeneous long-range corrections. We calculate the surface tensions without the need for explicit evaluation of the virial by using the wandering interface and test area methods. Comparison with surface tensions obtained previously for chains of truncated Lennard-Jones beads show a very large contribution of interactions beyond truncation radii as large as four bead diameters. The percentage change is about 40% for low temperatures but may increase beyond 60% for high temperatures, thus revealing the need for proper account of long-range corrections for models with untruncated interactions. The study of interfacial properties with chain length shows asymptotic increase for the surface tension and related asymptotic decrease for the interfacial width.