ResearcherIDGoogle Scholar Reference
A short overview of research topics is given in the following.
The snapshot on the right is taken from a computer simulation of
a mixture of hard spheres and hard rods that displays phase separation.
Colloidal rod-sphere mixture.
Basic model fluids
Density functionals were constructed for hard spheres  ,
penetrable spheres that interact with a step-function pair potential
 (see  for more discussion), the Asakura-Oosawa-Vrij model of
colloid-polymer mixtures , the Widom-Rowlinson model , and
non-additive hard sphere mixtures .
The density functional theory for the Asakura-Oosawa model of
colloid-polymer mixtures  was used to find the "floating liquid"
phase . Phew, I am exhausted! All these relations drive me
crazy.. See  for an investigation of bulk fluid phases. See
 for an answer to the question whether effective interactions
depend on the choice of coordinates.
Colloid-polymer mixtures: Beyond the AOV model
Extensions include taking into account an explicit solvent of point
particles , penetrability of (small) colloids into polymers ,
colloid-induced polymer compression , the influence of polymer
interactions on fluid-demixing  and on the contact angle of the
colloidal liquid-gas interface and a hard wall , as well as the
stability of the floating liquid phase in sedimenting colloid-polymer
mixtures for non-ideal polymers .
DFT for soft potentials
Based on the hard sphere case  , a density functional theory
(DFT) for soft (i.e. continuously varying as a function of
interparticle distance) potentials was obtained by considering
dimensional crossover , and subsequently extended to mixtures
. Applications concern the liquid structure of model fluids ,
and structure and freezing of star polymer solutions  (see also
Colloid-polymer mixtures display fluid-fluid interfaces  ,
relevant for laser-induced condensation , capillary condensation
 and evaporation , immersion in porous media , the
appearance of the floating liquid phase , the competition between
sedimentation and phase coexistence , tension at a substrate ,
the experimental observation of thermal capillary waves ,
and the contact angle of the liquid-gas interface and a wall . In
colloidal rod-sphere mixtures fluid-fluid interfaces were investigated
with theory  and simulation . Hard sphere fluids were
considered at surfaces of porous media , in random fiber networks
, and in one dimensional cases .
Fluids in random media
The density functional theory for quenched-annealed mixtures 
relates the quenched components to a random porous medium and the
annealed components model to an adsorbate fluid (mixture). See 
for the explicit relation to the the replica trick.
Colloid-polymer mixtures were studied in bulk random matrices
, exhibiting (gas-liquid) interfaces , and wetting properties
at porous substrates . Rods were immersed in quenched
sphere matrices , and spheres were immersed in random fibre
networks . Freezing is hindered in the presence of disorder
. See  for the related non-equilibrium process of random
Hard core amphiphiles.
A model amphiphilic hard body mixture of spheres (o), needles (-), and
lollipops (o-)  was used to investigate ordering of amphiphiles at
a hard wall (|o-)  and at fluid interfaces .
The hard sphere system freezes between  and , and in ~
dimensions (tags as contents!), as well as on stripe-patterned
substrates . Deep relations to dimensional crossover exist 
. Hard spheres were immersed in emulsions , confined to a
flexible container , exposed to surfaces of other quenched spheres
 and of random fiber networks , and subject to gravity
. Recently, the Rosenfeld functional   was generalized to
non-additive mixtures .
For hard spherocylinders the bulk phase diagram (Ref.4), topological
defects in nematic droplets , and the isotropic-nematic transition
inside random sphere matrices  was considered.
The DFT of  was extended to treat rod-rod interactions  ,
and used for free fluid interfaces  and wetting at a hard wall
. Simulations  confirmed unusual interfacial rod ordering. See
 for the demixing phase behavior of the system upon adding
Legal. The material on this website is intended as a scientific
resource for the private use of individual scholars. None of it may be
used commercially, or for financial gain. Some of the material is
protected by copyright. Requests for permission to make public use of
any of the papers, or material therein, should be sought from the
original publisher, or from M. Schmidt, as appropriate.
MS, 9 Jun 2021.