N ov 2 00 9 Phase behavior of a confined nano - droplet in the grand - canonical ensemble : the reverse liquid - vapor transition

The equilibrium density distribution and thermodynamic properties of a Lennard-Jones fluid confined to nano-sized spherical cavities at constant chemical potential was determined using Monte Carlo simulations. The results describe both a single cavity with semipermeable walls as well as a collection of closed cavities formed at constant chemical potential. The results are compared to calculations using classical Density Functional Theory (DFT). It is found that the DFT calculations give a quantitatively accurate description of the pressure and structure of the fluid. Both theory and simulation show the presence of a “reverse” liquid-vapor transition whereby the equilibrium state is a liquid at large volumes but becomes a vapor at small volumes. PACS numbers: 61.46.-w,64.70.Nd,05.20.Jj Submitted to: J. Phys.: Condens. Matter Confined nano-droplet 2