
%0 Journal Article
%A Nordholm, S 
%A Gibson, J 
%T Generalized van der Waals theory. VII. Interface profiles and surface tension
%J Australian Journal of Chemistry
%D 1981/11/01
%V 34
%N 11
%P 2263-2282
%K 
%R https://doi.org/10.1071/CH9812263
%U https://www.publish.csiro.au/paper/CH9812263 
%X An equilibrium theory of fluids based on a simple free-energy density functional developed and tested in several preceding articles is here applied to estimate the shape and surface tension of a gas/liquid interface in a simple LJ(12-6) fluid. The calculation is carried out at several different levels of approximation. In the simplest case when a step function profile is assumed the surface tension is obtained analytically. It is too high by about 50%. By using a moment expansion of the nonlocal free energy functional, the surface tension can be reduced to a simple one-dimensional integral. The result is now only slightly high. Finally, a variational calculation assuming a tanh form for the profile has been carried out. The effect of nonlocal entropy is examined and found to cause a drop in the surface tension by 5-10%. The results for the surface tension and width of the profile are in good agreement with experiment and simulation (deviation c. 0%) when plotted against T/Tc. 
