Dr. Jan-Ole Joswig

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Global Geometry Optimization Approaches

If a system consists of more than, say, twenty atoms, and chemical knowledge doe not help in determining its structure, global geometry optimization may be helpful. In particular, clusters and nanoparticles built from metal atoms have been studied with this approach. Thereby, we have developed a genetic algorithm in combination with a fast electronic-structure method (DFTB) to study, e.g., so-called metcar (titanium-cabon) clusters.
Other search algorithm that we have developed focus more on a growth-approach, so that the actual growth process in an experiment can be replicated. Besides their mathematical fascination, global-geometry algorithm are very helpful tools for all kind of optimization problems.

» Selected references:

• The influence of C₂ dimers on the stability of Ti_mC_n metcar clusters,
  J.-O. Joswig and M. Springborg,
  J. Chem. Phys. 129 (2008), 134311/1-7,
  also: Virtual J. Nanoscale Sci. Technology 18/16 (2008).
• Photo-absorption in sodium clusters on the basis of time-dependent density-functional theory,
  J.-O. Joswig, L.O. Tunturivuori, and R.M. Nieminen,
  J. Chem. Phys. 128 (2008), 014707/1-6.
• Size-dependent structural and electronic properties of Ti_n clusters (n<100),
  J.-O. Joswig and M. Springborg,
  J. Phys.: Condens. Matter 19 (2007), 106207/1-18.
• A genetic-algorithms search for global minima of aluminum clusters using a Sutton-Chen potential,
  J.-O. Joswig and M. Springborg,
  Phys. Rev. B 68 (2003), 085408/1-9.
• Structural and electronic properties of small titanium-carbon clusters (metcars),
  J.-O. Joswig, M. Springborg, and G. Seifert,
  Phys. Chem. Chem. Phys. 3 (2001), 5130-5134.