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. |
 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. |
 Charge fluctuations in Yb f-shell |
Fluctuating
vs intermediate valence - valence transition in Yb under pressure The 4f shell of Yb can
accomodate 13 or 14 electrons depending on a particular compound. This
near degenracy of f13 and
f14 valence
states has deep consequences. Using LDA+DMFT we instigate continuous
transition between the f13
and f14 valence
states in elemental Yb induced by pressure and discuss it in terms of fluctuating and intermediate valence concepts.
Fluctuating valence and valence transition in Yb (presentation pdf) |
 Pyrite crystal structure of NiS2 |
Metal-insulator
transition in NiS2-xSex The
NiS2-xSex solid solution provides a model system where the trantion
between metallic phase and the Mott insulator can be tuned by Se
content, pressure or temperature. Using LDA+DMFT we show that, contrary
to common claims, the transition is essentially controlled by varying
hybridization gap within the S(Se) p-band related to the bond length
of the S-S (Se-Se) dimer.
Is NiS2 a charge-transfer insulator? (presentation pdf) |
 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 |
Pushing my grade in trad climbing |