
Research Interests
My main research interests are groundstate and spectral (dynamical)
properties of complex quantum manyparticle systems  such as
solids, quantum
liquids, quantum spin chains or plasmas  with an emphasis on
 interplay of spin, charge, lattice and orbital degrees
of freedom in
materials with strong electronic correlations
(heavy fermions, hightemperature
superconducting cuprates,
colossal magnetoresistive manganites, chargeordered
nickelates,...)
 quasi1D electron/spinphononsystems
(symmetrybroken ground states, Peierls
& spinpeierls instabilties, intrinsic localized
vibrational modes, Luttinger
liquid behaviour, spinchargeseparation, metalinsulator &
insulatorinsulator transitions,...)
 disorder effects (Anderson localization, percolation,
frustration, spin
glasses,...)
 magnetic shortrange order in itinerant electron systems
 polaron, bipolaron &
exciton formation (selftrapping transition, optical
response, polaronic superlattices, excitonic insulators,
BoseEinstein condensation,...)
 complex electronhole plasmas
In all projects, we want to gain insight from a microscopic
point of view.
We employ modern analytical and numerical techniques of quantum
theory of many
partical systems. Among others, we use
 functional integral (slavefield) methods,
 Green'sfunction projection approaches,
 unitary transformation schemes,
 Lanczos & JacobiDavisdon diagonalizations,
 kernelpolynomial expansion & maximum entropy methods,
 density matrix renormalisation group.

