The proposed project concerns theoretical modelling using ab initio quantum-chemical methods of defects at oxide surfaces. Different types of defects will be modelled, for example point defects like interstitial atoms, vacancies or substitutions, and topological defects like kinks, steps and edges. Especially will F-centres be studied. In these, an electron is trapped and localized at the site of an anion vacancy, and due to the unpaired spin the defect is paramagnetic. The oxide systems to be studied are MgO, a-A1203 and different forms of silica, such as quartz. The computational methods will be periodic HartreeFock calculations, which makes ab initio calculations at 3-dimensional crystals or 2-dimensional surfaces possible, and perturbed-cluster computations, which is designed for calculations of local perturbations in a crystalline environment. Both methods have been developed largely at TODipIFM. The structures, formation energies, distributions and chemical activities of the various defects will be investigated and characterized by these methods. Spin densities will be calculated and comparisons will be made with experimental electron paramagnetic resonance (EPR) spectra.
Training content (objective, benefit and expected impact)
The group of Prof. Pisani is one the leading groups in the area of theoretical solid-state chemistry. Both the periodic HartreeFock and the "perturbed-cluster" methods are state-of-the-art in the field. Important contributions have been given by this group for example in the understanding of the chemical and physical properties of semiconductors and mixed ionic-molecular crystals, and lately also in the elucidation of reaction mechanisms in solids and at surfaces. It is likely that the applicant will much benefit from working with Prof. Pisani and acquire knowledge that later can be of great value not the least for his department back home in Sweden.
Links with industry / industrial relevance (22)
Material science investigations often lead to industrial applications. In this study we apply and develop powerful and novel computational techniques, that are likely to become mainstream in the categorisation of properties of new materials in the future. The materials studied (e.g. MgO, SiO2, Al2O3) are technologically important.