Thomas Wüst, PhD

Contact Information:

The Center for Simulational Physics
Department of Physics and Astronomy
The University of Georgia
Athens, GA 30602-2451, USA

Phone: +1 706-542-3867
Email: email-address

Research Interests:

Investigating complex physical systems by developing mathematical/computational models and evaluating their usefulness. On the basis of such models, characterizing principal properties and determining the forces governing them by means of analytical and computational methods. Connection between physical concepts, computational methods and the human.
Physics (Statistical) physics of condensed matter (e.g. crystals, polymers, spin systems/magnetism, soft matter); cooperative/critical phenomena (e.g. phase transitions); non-equilibrium, irreversible and growth processes; dynamical systems and chaos; pattern formation.
Mathematics Markov chains and stochastic processes; vector and differential geometry; fractals.
Computational Monte Carlo and other computational/simulational techniques (e.g. molecular dynamics, quantum chemistry methods); optimization; numerical analysis; graphical visualization; artificial intelligence (e.g. neural networks, cellular automata, machine learning); high performance computing.
Interdisciplinary Materials science; electronics (e.g. digital/integrated circuits); biomedical engineering (e.g. hearing aids); computational neuroscience.

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Recent Projects:

Monte Carlo Simulations in Biological Physics

Coarse-grained simplified models play an important role for the understanding of the complexity of biological phenomena such as protein folding and Monte Carlo simulation methods are an indispensable tool for the study of such models. The hydrophobic-polar (HP) lattice protein model (Lau & Dill, Macromolecules 22, 1989) has gained much attention as a standard in assessing the efficiency of computational methods for protein structure prediction as well as for exploring the statistical physics of protein folding in general. Within a minimalistic framework, it features some of the biggest challenges for the computational study of proteins and many other complex systems: namely, the efficient sampling of a large conformational space characterized by a rough energy landscape with many local minima and high energy and/or conformational barriers.

This project includes:

HP 20mer in 2D (H: white beads; P: blue beads)
Click on image for an animation

Ground state of a HP 103mer in 3D


Growth-Induced Polarity Formation in Molecular Crystals

Symmetry breaking at the surface during growth of molecular crystals can induce macroscopic physical properties (e.g. polarity) which may not be allowed by the symmetry group of the bulk. This phenomenon has been observed experimentally in single-component crystals, inclusion compounds and solid solutions of organic dipolar molecules. Theoretically, evolution of growth-induced polarity can be described by a stochastic growth process, in its simplest form by a layer-by-layer growth model, where subsequent ad-layers of dipolar molecules thermalize on a frozen substrate (see Hulliger et al., Chem. Mater. 14, 2002; Bebie et al., Phys. Rev. E 66, 2002).

This project includes:

Monte Carlo simulation of polarity formation in solid solutions H1-XGX (blue/red squares: dipolar H molecules with dipole orientation down/up, resp.; yellow squares: non-polar G molecules)

Click on images for an animation

Ad-layer
(top view of crystal surface)

Cross-section
(view along growth direction)

Solid lines: mean-field approximation;
dots: Monte Carlo simulations

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Formation:

2006 Postdoctoral research position at the Center for Simulational Physics, University of Georgia, USA.
Advisor: Prof. David P. Landau.
Subjects: Development of Monte Carlo simulation methods for protein structure prediction; statistical physics of simplified protein models.
2002 - 2005 PhD thesis in Physics. Department of Chemistry and Biochemistry, University of Bern, Switzerland.
Supervisor: Prof. Jürg Hulliger.
Title: Growth-induced polarity formation in molecular crystals: Analytical theory and Monte Carlo simulations.
2000 - 2002 PhD student at the Department of Chemistry, Swiss Federal Institute of Technology (ETH) Zurich, Switzerland.
Subject: Quantum chemical ab initio calculations of interaction energies between dimer radicals.
1993 - 1999 Master of Science in Physics. Swiss Federal Institute of Technology (ETH) Zurich, Switzerland.
Master's thesis: Simulation of a stellar convection zone. Institute for Astronomy, ETH Zurich.

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Award:

Jan. 2006 Faculty prize 2005 for the PhD thesis from the Faculty of Science (Chemistry and Biochemistry), University of Bern, Switzerland.

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Publications:

  1. T. Wüst and D. P. Landau. The HP model of protein folding: A challenging testing ground for Wang-Landau sampling. Comput. Phys. Commun. in press.

  2. Y. W. Li, T. Wüst, D. P. Landau, H. Q. Lin. Numerical integration using Wang-Landau sampling. Comput. Phys. Commun. 117, 524 (2007).

  3. T. Wüst and J. Hulliger. Effect of reduced cooperativity on growth-induced polarity formation: A comparison between different growth models. Phil. Mag. 87, 1683 (2007).

  4. T. Wüst and J. Hulliger. Growth-induced polarity formation in two-component crystals of organic molecules: A statistical analysis. J. Phys. Chem. Solids 67, 2517 (2006).

  5. T. Wüst and J. Hulliger. Growth-induced polarity formation in solid solutions of organic molecules: Markov mean-field model and Monte Carlo simulations. J. Chem. Phys. 122, 084715 (2005).

  6. T. Wüst, C. Gervais, J. Hulliger. How symmetrical molecules can induce polarity: On the paradox of dilution. Cryst. Growth Des. 5, 93 (2005).

  7. C. Gervais, T. Wüst, J. Hulliger. Influence of solid solution formation on polarity: Molecular modeling investigation of the system 4-chloro-4'-nitrostilbene/4,4'-dinitrostilbene. J. Phys. Chem. B 109, 12582 (2005).

  8. C. Gervais, T. Wüst, N. R. Behrnd, M. Wübbenhorst, J. Hulliger. Prediction of growth-induced polarity in centrosymmetric molecular crystals using force field methods. Chem. Mater. 17, 85 (2005).

  9. J. Hulliger, M. Losada, C. Gervais, T. Wüst, F. Budde. Effects of an external electrical field on the polarization of growing organic crystals: A theoretical study. Chem. Phys. Lett. 377, 340 (2003).

  10. H. I. Süss, T. Wüst, A. Sieber, R. Althaus, F. Budde, H. P. Lüthi, G. D. McManus, J. Rawson, J. Hulliger. Alignment of radicals into chains by a Markov mechanism for polarity formation. CrystEngComm 4, 432 (2002).

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Last update: May 18, 2008