# Dresden 2006 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

# CPP: Chemische Physik und Polymerphysik

## CPP 12: POSTER Colloids, Nanoparticles and Self-Organizing Systems

### CPP 12.4: Poster

### Dienstag, 28. März 2006, 17:00–19:00, P3

**A fundamental measure free-energy functional for nonspherical particles** — •Hendrik Hansen-Goos^{1,2} and Klaus Mecke^{3} — ^{1}Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart — ^{2}ITAP, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart — ^{3}Institut für Theoretische Physik, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058 Erlangen

In 1989, Y. Rosenfeld established his fundamental measure theory (FMT)
free-energy functional for the hard-sphere fluid. The starting point for his
derivation is an exact decomposition of the Mayer-*f*-bond in terms of
convolutions of scalar and vectorial weight functions leading him to an excess
free-energy function of scalar and vectorial weighted densities. Rosenfeld’s
free-energy has proved to describe very accurately inhomogenous hard-sphere
fluids and it is conveniently
tractable computationally as only one-center convolutions are involved. Later
on, a generalisation of his original FMT to nonspherical particles was given by
Rosenfeld himself. Unfortunately, the theory does not show an
isotropic-nematic transition as observed, e.g., for hard spherocylinders or
ellipsoids. Other free-energy functionals that do predict an isotropic-nematic
transition generally involve two-center convolutions and therefore demand more
computational efforts. Starting from the exact expression for the
Mayer-*f*-bond for convex particles we introduce an approximate decomposition
leading us to a new free-energy functional for non-spherical particles. The
functional is still based on one-center convolutions and can be shown to yield an
isotropic-nematic transition for spherocylinders. Strategies to enhance the
agreement with simulation data are presented.