IFF
Scientific Report 1998/1999

Institute Theory II: Overview.

The Institute Theory II of the IFF is in a transitional phase. Following a prolonged period of interim administration the Institute will acquire a new leader, Dr. G. Gompper (MPI-KG Teltow), who will assume the Directorship in March 1999. Dr. Gompper's main research interests are in the field of soft matter theory, especially microemulsions. It is therefore to be expected that in the future the activities of the Institute will be focussed on these and related topics.

Traditionally, the research activities of Institute Theory II members have been centred on the investigation of the structure and dynamics of soft- and solid-matter. These activities have contributed to the R&D programmes `Cooperative Phenomena in Condensed Matter' and `Polymers, Membranes and Complex Fluids' of the Jülich Research Centre. The work has used numerical techniques to a considerable extent, but has also involved analytic methods wherever this is practical.

One major activity in recent years was the investigation of transport and relaxation processes of particles in disordered media with and without lattice translational invariance. Energetic relaxation processes have been studied in simple hopping models with the aim of elucidating the nature of slow dynamical processes that are observed in glass-forming substances. Further, motional processes as probed by two-dimensional magnetic resonance are being studied in different models of polymer melts. Research into transport and relaxation processes of particles in condensed matter will be reduced considerably on the retirement of Prof. K. Kehr this summer.

Another important activity in Theory II is the study of non-equilibrium behaviour of strongly interacting many-body systems. Major progress has been made in this field in recent years through the development of abstract analytical methods. This progress is documented in the habilitation thesis of Dr. G. Schütz, who has made essential contributions to this field. The abstract methods developed for these many-body systems enable a variety of applications including the treatment of soft-matter. Examples are the relaxation and mobility of long entangled polymers under various external conditions eg. in gel electrophoresis. The development of lattice-gas models for semi-flexible polymers is planned for the future.

Biophysical problems are studied by Dr. A. Baumgärtner. He is currently a member of the `Modelling Forum' and his research activities are tied to the R&D programme of the Forum.

A guest group under the scientific leadership of Prof H. Löwen (University of Duesseldorf) formed part of the Institute Theory II from November 1995 until December 1998. The work of this group focussed on the statistical mechanics of colloidal suspensions and the methods employed included liquid-state integral equations and density-functional theory as well as computer simulations. Examples for recently investigated problems are i) the stability of colloidal quasicrystals ii) the structure of star-polymer solutions and iii) the dynamics of confined systems in two- and three-dimensions. In its three years existence, Prof. Löwen's group contributed greatly to the activities of Institute Theory II in the field of soft-matter during this period of transition.

(b) Guests

(c) Graduate students