Sodium bismuth titanate (NBT) belongs to the class of the ABO_{3} 
perovskites and is ferroelectric at room temperature. Thus, it is a 
promising candidate for a lot of technological applications.


 In this work we want to study at first the formation of \NBT\ on the 
common substrates such as strontium titanate (STO) and strontium 
ruthenate (SRO) by means of Density Functional Theory. The challenge 
of this task is posed by the vast complexity of the system, which 
demands to take a lot of different atomic configurations of ad-atoms 
and molecules of the surface into account. We will study the 
thermodynamic stability of these configurations and our aim is to 
provide a phase-diagram, indicating the conditions on which growth of 
NBT should be observed. The knowledge of the thermodynamic stable 
configurations is a prerequisite for developing a microscopic model 
which describes the formation of oxygen-based perovskites. This issue 
is closely related to the experimental work in the group of Prof. 
Fornari. 


 The second aim of this work is to study the structural, electronic 
and dielectric properties of NBT also by means of DFT. For this 
material, this has not been done so far and it is supposed to provide 
knowledge, how its dielectric properties may be influenced by 
pressure, strain or impurities.