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My research focuses on the thermodynamic properties and phase behavior of materials, with a strong emphasis on complex fluids, such as polymeric systems and electrolytes. These systems are studied predominantly by means of computer simulations, through which we aim to realize our primary goals: First, to understand experimentally observed phenomena from the underlying microscopic features of a system, and second, to test the predictive value of analytic theories describing these systems. The insight thus gained allows the prediction of yet unknown properties of materials and the design of new materials.

Current research projects concern the properties of electrolyte solutions near their critical point and the phase behavior of ternary polymer solutions as a function of the degree of polymerization. In addition, concrete plans exist for the study of other, closely related, polymer mixtures. I anticipate that in the immediate future the center of my research will shift to various charged systems, including those involving colloids and polyelectrolytes. Not only do these systems exhibit fascinating properties stimulating our scientific curiosity, but they are also strongly gaining importance in nanotechnological and bioengineering applications.

Despite the steady increase in available computer power, many of these problems hover on the verge of what is feasible. Therefore, in order to obtain scientifically worthwhile results within an acceptable time frame, it is essential to employ state-of-the-art techniques. We take an active interest in the development of new methodologies, both simulation techniques and advanced approaches to data analysis. One breakthrough has been the development of a Monte Carlo algorithm for long-range ferromagnetic and dipolar spin models, which has sped up simulations of these systems by many orders of magnitude and which is now the method of choice in studies of this class of systems.

Past highlights of my research lie in the area of theoretical statistical physics, primarily in the field of critical phenomena. These include:

• The demonstration that one of the basic models for surface roughening incorporates an inverse roughening transition, where a crystal surface is smooth at low temperatures and becomes rough at higher temperatures.
• The first explicit numerical evidence that simple one-dimensional systems can exhibit the celebrated Kosterlitz-Thouless transition, which describes phenomena such as surface melting, the lambda transition in superfluid films, and the normal-superconductor transition in two-dimensional superconductors.
• The first numerical calculation of crossover scaling functions describing the crossover between different universality classes in the vicinity of a continuous phase transition. In addition to the verification of theoretical predictions, these functions have been used for the description of experimental data for helium and xenon.
• The exact solution of a class of systems with long-range (power-law) interactions, proving that these nonextensive models can be described by Boltzmann-Gibbs statistics.
• Contributions to the elucidation of finite-size scaling theory in the absence of hyperscaling and resolution of various controversies regarding the numerical verification of predictions made by the renormalization-group theory in this regime.