Molecular dynamics simulations of crystallization under confinement at triple point conditions

Molecular dynamics computer simulations of crystallization of a Lennard-Jones system under confinement conditions in the vicinity of the triple point are reported. We calculate the force exerted on a crystal by a melt when it crystallizes. The force due to crystallization is reflected in the disjoining pressure isotherms as a characteristic peak. We find that at conditions of high confinement, i.e., pore thicknesses of approximate to1 nm, the disjoining pressure can rise up to approximate to10(8) Pa. We also analyze the dependence of the crystallization under confinement as a function of temperature. Confinement can stabilize the crystal phase at temperatures significantly higher than the melting temperature. For the systems studied in this work, a pore of 1 nm thickness stabilizes the crystal phase at temperatures up to 45% higher than the normal melting temperature. In addition we consider the disjoining pressure profile along confining pore slits of finite lengths. The finite size effects due to the pore length modifies the value of the force close to the pore edge. There exist a reduction of the total disjoining pressure in short pores with respect to long pores. The simulations show that these effects are more noticeable for pore lengths below 3 nm. (C) 2003 American Institute of Physics.