## 12. Ab-initio calculation of materials properties

Ab-initio modelling and calculation of materials properties is a fast growing field because of the success of its computational tools. One tries to understand and describe the properties of materials purely on the basis of quantum physics without the usage of any empirical parameter: the bonding between the atoms of the materials is derived from the solutions of Schr¨odinger’s equation.

Within density functional theory the basic quantities calculated are the total energy and the electronic structure of the system under study which enable the derivation of a large variety of properties such as structural and phase stabilities, surface and interface energies and properties, adsorption of molecules, equilibrium structures, defect properties, segregation, elastic, vibrational and mechanical properties, magnetic phases, spectroscopical quantities, and so on.

The investigations of the Redinger group within the CMS are often done in close collaboration with experimental groups and are based mainly on two DFT codes: on the Vienna Ab initio Simulation Package, VASP [G. Kresse, Vienna University], one of the most powerful packages worldwide routinely capable to treat large simulation cells (> 200 atoms) and our own implementation of the FLAPW formalism in the FLAIR package ( 60 atoms). Presently, we focus on a variety of surface and bulk systems: (i) Halogen and Hydrogen adsorbate systems on Platinum surfaces, to understand the interplay between adsorbate and substrate regarding the phase stabilities. (ii) Structural properties of superconducting 482 ring boro-carbides of MB2C2 type (M=metal), to understand the connection between boron-carbon ordering and physical properties. (iii) Exotic magnetic properties of bulk and surfaces, including magnetism without d-electrons and intrinsic magnetic surfaces of non-magnetic bulk materials. (iv) Interface studies on nano-structured TiN/VN multilayers, to develop a fundamental understanding of the atomic processes controlling the kinetics of V diffusion through the TiN layers to form a self-lubricating surface layer. Immediate and future cooperations are to be expected with the Blaha, Mohn, Held and Kozeschnik groups. Also collaborations with numerical mathematicians are always welcome and would be beneficial in the further development of FLAIR.