Description
We present an original method for the accurate quantum treatment of the planar
three body Coulomb problem under electromagnetic driving. Our ab initio approach combines Floquet theory, complex dilation, and the representation of the Hamiltonian in suitably chosen coordinates without adjustable parameters.
The resulting complex-symmetric, sparse banded generalized eigenvalue problem
of rather high dimension is solved using advanced techniques of parallel
programming.
In the present thesis, this theoretical/numerical machinery is employed to
provide a complete description of the bound and of the doubly excited spectrum of the field-free 2D helium atom. In particular, we report on frozen planet
quantum states in planar helium.
For the driven atom, we focus on the near resonantly driven frozen planet
configuration, and give evidence for the existence of nondispersive
two-electron wave packets which propagate along the associated periodic orbit. This represents a highly nontrivial qualitative confirmation of earlier calculations on a 1D model atom, though with important enhancements of the
decay rate of these atomic eigenstates in the field, due to the transverse
decay channel. The latter is already found to enhance the decay rates of the
unperturbed frozen planet as compared to the 1D model, in surprisingly good quantitative agreement with 3D results.
Die moderne Astrophysik steht vor der Herausforderung, neueste
Beobachtungen mit den theoretischen und numerischen Modellen der
Galaxienentstehung und -entwicklung zu konfrontieren. So hofft man, die
wichtigsten physikalischen Prozesse und ihre Zeitskalen identifizieren zu
koennen.
In dieser...
Published 09/10/04
This work presents the results of a detailed study of the statistical and physical properties of binary ultracool dwarfs and brown dwarfs (spectral type later than M7).
As for the statistical properties, we found that the frequency of binaries among ultracool objects is significantly lower than...
Published 09/04/04