Most of the technological materials have been developed by very expensive and cumbersome trial and error methods. On the other hand, computer based theoretical design of advanced materials is an area where rapid and extensive developments are taking place. Within my group new theoretical tools have now been established which are extremely well suited to the study of complex materials. In this approach basic quantum mechanical theories are used to describe fundamental properties of alloys and compounds. The utilization of such calculations to investigate possible optimizations of certain key properties represents a major departure from the traditional design philosophy. The purpose of my project is to build up a new competence in the field of computer-aided simulations of advanced materials. The main goal will be to achieve a deep understanding of the behaviour of complex metallic systems under equilibrium and non-equilibrium conditions at the atomic level by studying their electronic, magnetic and atomic structure using the most modern and advanced computational methods. This will enable us to establish a set of materials parameters and composition-structure-property relations that are needed for materials optimization. The research will be focused on fundamental technological properties related to defects in advanced metallic alloys (high-performance steels, superalloys, and refractory, energy related and geochemical materials) and alloy phases (solid solutions, intermetallic compounds), which will be studied by means of parameter free atomistic simulations combined with continuum modelling. As a first example, we will study the Fe-Cr system, which is of great interest to industry as well as in connection to nuclear waste. The Fe-Cr-Ni system will form another large group of materials under the aegis of this project. Special emphasis will also be placed on those Fe-alloys which exist under extreme conditions and are possible candidates for the Earth core.