number of molecules because it is time consuming. At this We have made an estimation of the interfacial tension of octane/ moment it is not applicable to calculate interfacial tension water system based on the molecular dynamics simulations. The of systems including a large number of molecules.
interfacial energy is the surface excess of internal energy, while
The interfacial tension is the surface excess of Helmholtz the interfacial tension is the surface excess of Helmholtz free enfree energy whose evaluation is generally difficult. It inergy whose evaluation is generally difficult. The potential of mean cludes the entropy effect due to molecular rearrangement by force (pmf) of solutes gives the intermolecular interaction which interface formation. Nevertheless, the values of interfacial includes the Helmholtz free energy change due to the rearrangement of solvent molecules; then it is expected to give the interfacial tension of alkane/water such as hexane/water or solid-paraftension. We calculated the stabilization energy of an octane pair fin/water and so on are similar, about 50 erg/cm 2 ; therefore, using the pmf, the decrease of the solvent-accessible surface (SAS) we assumed that the entropy effect of alkane rearrangement area of the octane pair for contacting, and the value which is the at the interface is a minor part of the interfacial tension. The stabilization energy of the octane pair divided by the change of potential of mean force (pmf) of solutes in water gives the the SAS area with some corrections, and it should correspond to intermolecular interaction energy which includes the free the interfacial tension. The calculated value was 57 { 11 erg/cm 2 energy change by the rearrangement of solvent molecules; which is close to the macroscopic interfacial tension of 50.8 erg/ then it is expected to give the interfacial tension. Sinanoglu cm 2 .