Computer simulation of the liquid-vapour interface in liquid crystals

We present a computer simulation study of the liquid-vapour interface for a fluid characterized by anisotropic interactions. This model has been shown to be suitable for studying liquid crystal phases. In this work we focus on interfacial properties such as orientational effects at the interface and the dependence of the surface tension with temperature. At all temperatures reported here, the liquid in coexistence with vapour is always orientationally disordered, although some evidence of smectic order at the lowest temperatures is observed. For the higher temperatures, no clear orientational effect is observed at the interface; however, as the temperature is decreased towards the vapour-isotropic liquid-smectic triple point, molecules tend to orient themselves at the interface. The surface tension values reported in this work seem to be in qualitative agreement with the anomalous behaviour observed for this quantity in the vecinity of the triple point in liquid crystals.