Dresden 2009 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 20: Poster Session I
MM 20.16: Poster
Dienstag, 24. März 2009, 14:45–16:30, P4
From DFT to TB: A reliable derivation of tight-binding parameters for hard materials — •Martin Reese1,2, Matous Mrovec1,2, Bernd Meyer3, and Christian Elsässer2 — 1IZBS, Universität Karlsruhe — 2Fraunhofer-Institut für Werkstoffmechanik IWM, Freiburg — 3ICMM, Universität Erlangen-Nürnberg
Hard materials play an important role in industrial applications as protective coatings of tools. Recent experiments indicate that nanostructered composites of crystalline and amorphous carbides and nitrides can yield materials that reach the limit of super-hardness. However, a scientific understanding of these complex materials is still incomplete.
In the course of developing a multi-scale modelling framework for simulations of nanocrystalline transition metal carbides and nitrides we apply accurate first-principles calculations, based on the density functional theory (DFT), to derive reliable non-orthogonal and orthogonal tight-binding (TB) Hamiltonians. The TB Hamiltonians are constructed by projecting the self-consistent electronic wave functions from DFT onto a minimum basis set of atomic orbitals. This well defined procedure enables to overcome the ad-hoc fitting of TB models and presents a rigorous coarse-graining tool, which can be applied in various bonding environments. In this contribution we will present the application of the method to several model materials, namely the covalently bonded elements carbon and silicon, the transition metal titanium, and binary compounds of these elements. We will discuss the variation of the Hamiltonian matrix elements as a function of the interatomic distance and their transferability in various environments.