Dr. Jan Kuneš
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Dr. Jan Kuneš
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Curriculum
Vitae Jan Kuneš studied physics
at the Faculty of Mathematics and Physics of the Charles University in
Prague in 1992-1997. After a brief
romance with experimental physics at the
University of Salford, U.K. he persued his
postgradual studies with Dr. Pavel Novák at the Institute of
Physics of the Czech Academy of Sciences in Prague and as a long-term
visitor at the Institute of Solid State and Materials Research in
Dresden. After finishing his PhD in 2002 he joined the group of Prof.
Warren Pickett at the University of California Davis where he stayed
till the fall of 2005. In 2006 joined Kuneš the Center for
Electronic Correlations and Magnetism at the University of Augsburg,
Germany, supported by the Alexander von Humboldt Research Fellowship
(2006-2007) and continued as a research associate.
In 2009 he was awarded the Purkyně Fellowship of the Czech Academy of Sciences. (cv) Kuneš's areas of research are computation of the electronic structure of materials using bandstrucutre methods (density functional theory), numerical many-body approaches to strong electronic correlations (dynamical mean-field theory, quantum Monto-Carlo methods), relativistic effects (spin-orbit coupling) and magnetism. |
 Local spin susceptibility reflecting a two-sublattice order at intermediate temperatures |
Electronic
correlations in systems with competing multiplets In
materials with strong electronic correlations only a small number of
atomic states are visited during quantum-meachnical and statistical
evolution of the system. Typically the belong to the lowest
N-electron multiplet of the corresponding valence and perhaps N+1 and
N-1 fluctuations around this state. In some materials hower, two (or
more) multiplets may happen to have comparable energies, which has
profound consequences. A prototypical examle is LaCoO3.
We use DMFT to investigate such systems both on model and material
specific level.
Susprising correlation effects in band insulators (presentation pdf) |
 Spin-up and down parts of the J=1/2 Wannier orbital |
Construction
of
Wannier orbitals with wien2k We have developed and interface
between the banstructre code wien2k and wannier90 software for
calculation of so called maximally localized Wannier orbitals. This
allows us to construct effective Hamiltonians of materials. One of the
first applications includes Ir compounds with strong spin-orbit
coupling where spin-projection is no more a good quantum number.
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 Closing of the charge gap in MnO |
Simultaneous spin
and Mott transition under pressure MnO is a prototypical Mott insulator,
which undergoes several transtions at high pressure (~ 100 GPa): structural
(NaCl -> NiAs structures), local moment collapse (HS -> LS
transition), volume collapse (within NiAs structure), Mott transtition
(insulator -> metal). Using combination of LDA hamiltonian and
dynamical mean-field theory (LDA+DMFTT approach) we study
nature and relationships of these transitions. Hematite (Fe2O3) is
isoelectronic to MnO and exhibits similar behavoir
Crystal-field driven Mott transition in MnO under pressure (presentation pdf) |
 Generalized bandstructure of NiO |
Dynamical
mean-field (LDA+DMFT) investigation of charge-transfer materials NiO is a prominent example of
so called charge-transfer insulator (a subset of Mott insulators). To
describe the physics of charge-transfer materials ligand state (oxygen
p-state here) must be explicitely included in the hamiltonian. Using
LDA+DMFT we study the single-particle spectra (PES, IBS, ARPES) of
stociometric and hole-doped NiO.
NiO - hole doping and bandstructure of charge-transfer insulator (presentation pdf) |
 3rd pitch of Freeblast, Yosemite |
Getting in shape for the
Nose-in-a-day |