1: Semiclassical theories
Collaborators: Profs. R.K. Bhaduri (McMaster Univ., Canada), M.V.N.
Murthy (IMSC, Madras, India), J. Law (Univ. of Guelph, Canada);
Dr. A. Sugita (Kyoto University, Japan);
Drs. A. Magner, D. Fedotkin and F. Ivanyuk (INR, Kiev);
Dr. S. Frauendorf (FZ Rossendorf), M. Sieber (Univ. Bristol);
Dr. O. Zaitsev, Dr. K. Tanaka,
Dipl.-Phys. Ch. Amann, J. Kaidel, M. Pletyukhov, Regensburg
Support: DFG, EU (TMR, INTAS), NSERC (Canada).
We develop semiclassical methods for describing finite bound fermion systems.
A: Extended Thomas-Fermi (ETF) model for average
properties (binding energies, densities). The ETF model is extended to
two-dimensional systems including magnetic fields and spin degrees
of freedom. B:
Periodic orbit theory (POT)
quantum shell effects. We study extensions of Gutzwiller's POT to include
continuous symmetries, symmetry breaking, bifurcations of classical orbits;
inclusion of external magnetic fields; grazing, diffraction and scattering
effects (e.g. from boundaries or from a magnetic flux tube); inclusion of
spin degrees of freedom (e.g. spin-orbit interactions).
We develop extensions to transport properties
and collective vibrations (linear response). Gross-shell properties
described by the shortest periodic orbits; coexistence of chaos and order
in non-integrable systems. In this context: study of non-linear dynamics
(in particular: bifurcations on the road to chaos).
For a textbook on "Semiclassical Physics", look here .
2: Physics of finite fermion systems
Collaborators: Profs. J. Meyer (Univ. Lyon-I), P.G. Reinhard (Univ.
Erlangen), M.V.N. Murthy (IMSC, Madras, India);
Drs. S. M. Reimann (Lund Inst. Technology, Sweden),
M. Sieber (Univ. of Bristol, UK);
Drs. M. Seidl, A. Sugita, K. Tanaka, O. Zaitsev,
Dipl.-Phys. M. Pletyukhov, Ch. Amann, J. Blaschke, P. Meier and
S. Kümmel, Regensburg
Support: DFG, EU (SCIENCE, INTAS).
We investigate properties of finite fermion systems (nuclei, metal clusters
and semiconductor quantum dots): masses, densities, deformations, collective
excitations; in particular shell effects. Fully microscopic selfconsistent
calculations are done in the Hartree-Fock (HF) approach with effective
Skyrme interactions for nuclei, and in the density functional (DFT) approach
in local density approximation (LDA) by solving the Kohn-Sham equations
in one, two and three dimensions. Accurate exchange-correlation functionals
in terms of Kohn-Sham orbitals are developed in particular for strongly
correlated electronic systems. Selfconsistent calculations for average
properties are done in the ETF model (see 1. above). Shell effects are obtained
quantum-mechanically with the Strutinsky shell-correction method and
semiclassically with the POT (see 1. above). Special topics in nuclei:
shapes of ground-states, isomers and during
In metal clusters: mass distributions and
magic numbers ;
ionization potentials and electron affinities; supershell structure;
Mie plasmon (resonance in photoabsorption cross section); deformations
through plasmon splitting; static polarizability; jellium model and beyond;
ionic structure through Monte-Carlo molecular dynamics with phenomenological
local pseudopotentials that are used consistently in bulk, atoms and clusters.
In quantum dots and other mesoscopic systems:
conductance oscillations in magnetic fields. See
here for an overview.
For an introduction "Semiclassical approaches to mesoscopic systems", look here .