Efficient and scalable global structure optimization

• Applicant: Professor Dr. Bernd Hartke
• Subject Area: Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280675984

Molecular clusters are not only the link between single molecules and bulk matter but also have direct relevance in many areas, including nanotechnology, heterogeneous catalysis, and climate research. Their structures and properties differ from that of single molecules and bulk matter, and often also from what is expected by chemical experience. Therefore, practically applicable cluster structure prediction is of prime importance. However, this is hard to achieve since the search space of cluster structures grows exponentially with cluster size. Hence, standard local optimization tools are grossly insufficient, but also the by now well established non-deterministic global optimization strategies (NDGO; e.g., evolutionary algorithms (EA)) become unwieldy for larger clusters. Nevertheless, this is exactly where cluster experiments need theoretical support. Therefore, the present project aims at increases in global cluster structure search efficiency and at improved connections between theory and experiment.Large parts of this project continuation are devoted to EA method development. For local optimization, algorithms exist that are both general and highly efficient. However, the "no free lunch" theorem has proven that this combination is impossible for NDGOs. There, high efficiency has to be achieved by exploiting application-specific features. Following this core idea, most development lines aim at higher efficiency by adapting the EA to the problem at hand. However, the non-trivial EA control that this entails is not forced upon the user; instead, the EA is instrumented to detect and to "learn" the necessary changes. Hence, it can be expected that the resulting adaptive EA will not only be more efficient but also easier to handle.Another part of EA method development and two EA applications focus on an area that is new for EAs, namely aggregation of medium-size organic molecules on surfaces. In the first project phase, we could already demonstrate that EAs are applicable and useful in this area. In the above sense (efficiency via problem-specific features), however, further method development is needed. The two applications will be conducted in close collaboration with ongoing experimental projects, on "smart surfaces" and on heterogeneous catalysis.

• DFG Programme: Research Grants
• International Connection: Netherlands
• Cooperation Partner: Dr. Johannes Dieterich