Oscillatory Melting Temperature of Stockmayer Fluid in Slit Pores

The melting transition of bulk and confined Stockmayer fluids (mu(2) = 1) is analyzed using molecular dynamic simulations. The solid-liquid coexistence temperature is evaluated using a modified three-stage pseudo-supercritical transformation path. The bulk melting temperature calculated using the aforementioned method agrees well with the literature value. Melting temperatures of the Stockmayer fluid confined in Lennard-Jones (LJ) 9-3 slit pore of pore size, H, varying from 6 to 20 molecular diameters are reported. For H <= 12 molecular diameters, the shift in the melting temperature for the Stockmayer fluid is oscillatory in nature with the inverse of the pore size. However, for higher H the shift in melting temperature obeys the Gibbs-Thomson equation. The thermodynamic melting temperatures of the Stockmayer fluid under confinement, for variable pore sizes, are found to be usually higher than that of the bulk fluid. The structural and orientational order parameters are also presented, which suggest similarity in the structures of confined LJ and confined Stockmayer fluids.