AN ORIENTATIONAL INSTABILITY AND THE LIQUID-VAPOR INTERFACE OF A DIPOLAR HARD-SPHERE FLUID

Investigating the stability of the dipolar hard sphere fluid by localizing the spinodal we found an additional instability for medium and typical vapor densities, an orientational instability with formation of aligned clusters. For liquid densities we find ordinary vaporization. Then we calculate the structure of the liquid-vapor interface of a dipolar hard sphere fluid in the spirit of the weighted density approximation (WDA) using an equation originally derived by Lovett, Mou, and Buff [J. Chem. Phys. 65, 570 (1976)] and Wertheim [J. Chem. Phys. 65, 2377 (1976)]. The surface tension is evaluated on the same level of approximation.