An approximate DFT-method to understand complex materials structures, properties
and functions

Thomas Frauenheim, frauenheim@phys.uni-paderborn.de, Bremen Center for
Computational Materials Science, Bremen University, Bibliotheksstrasse 1,
Bremen, 28359, Germany

An efficient density-functional theory approach known as density-functional
tight-binding method (DFTB) is introduced and applied to predictive simulations
of complex nanoscale materials and properties. Successful applications to
inorganic structures are shown to cover a broad spectrum of problems, ranging
from semiconductor growth through amorphous carbon phases with nanodiamond
nucleation to surface and interface design in semiconductor technology. Most
recently, we focus our research on nanofunctionalization of inorganic substrates
and organic-inorganic hybrid surfaces/interfaces. Approaching new frontiers the
DFTB-method is generalized to cover weak interactions which are crucial for
modelling of soft materials. By coupling to Molecular-Mechanics force-fields
DFTB provides an efficient computational tool for addressing large
technologically relevant materials and biomolecular systems. New developments in
time-dependent density-functional-theory further allow to study the interaction
of ultra-short intense laser pulses with materials and photo-induced chemical
processes. Additionally, the development of novel simulation tools combining
DFTB with Keldysh Greens function techniques will be described.