Large-Scale Coupled Cluster Calculations for real Materials

Tobias Schäfer is working at the Vienna University of Technology on the computational modeling of quantum phenomena in materials. At the atomic level, these quantum phenomena are described mathematically by the Schrödinger equation. The key here is to take into account the complicated interaction of electrons. However, a highly accurate description of the electronic correlations pushes even modern supercomputers to their limits. This is because the computational effort required to solve the Schrödinger equa tion grows exponentially with the number of interacting electrons. In the research project "Large-Scale Coupled Cluster Calculations for Real Materials", Tobias Schäfer aims at simulating quantum mechanical effects in surface catalysis as well as the calculation of weak bonds of layered two-dimensional materials induced by quantum fluctuations. However, due to the large number of atoms and electrons involved, quantitatively high -precision modeling of such situations is beyond what is feasible today. Theref ore, the first step of the research project is to develop a new, more efficient algorithm for the established coupled -cluster method for solving the Schrödinger equation of large periodic simulation cells. By combining different techniques, such as the exploitation of numerically sparse tensors or the approximation of selected mathematical expressions, memory requirements and computation time can be drastically reduced while maintaining the high accuracy of the coupled -cluster method. In cooperation with international research groups, the algorithm will be applied to the aforementioned quantum mechanical processes in a second step. In doing so, precise reference data for the formation of oxygen perturbations in surfaces of cerium oxide as well as for binding energies of two-dimensional materials will be calculated. While binding energies are relevant for the design of new functional materials, oxygen vacancies form the reactive sites in processes of heterogeneous catalysis, which are of high interest for science and industry.