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Aufsatz
Finite element method for the accurate solution of diatomic molecules
(1989)
We present the Finite-Element-Method (FEM) in its application to quantum mechanical problems solving for diatomic molecules. Results for Hartree-Fock calculations of H_2 and Hartree-Fock-Slater calculations of molecules like N_2 and C0 have been obtained. The accuracy achieved with less then 5000 grid points for the total energies of these systems is 10_-8 a.u., which is demonstrated for N_2.
Aufsatz
H_2 solved by the finite element method
(1987)
We report on the solution of the Hartree-Fock equations for the ground state of the H_2 molecule using the finite element method. Both the Hartree-Fock and the Poisson equations are solved with this method to an accuracy of 10^-8 using only 26 x 11 grid points in two dimensions. A 41 x 16 grid gives a new Hartree-Fock benchmark to ten-figure accuracy.
Aufsatz
Autoionization and fragmentation of Na_2 studied by femtosecond laser pulses
(F. Ehlotzky (Ed.), 1989)
Aufsatz
State dependent volume isotope shift analysis of the low lying states of Ba I and Ba II
(1983)
Relativistic multi-configuration Dirac-Fock wavefunctions, coupled to good angular momentum J, have been calculated for low lying states of Ba I and Ba II. The resulting electronic factors show good agreement with data derived from recent high-resolution laser spectroscopy experiments and results from a comparison of muonic and optical data.
Aufsatz
Non-relativistic and relativistic molecular calculations for the chalcogen hexafluorides: SF_6, SeF_6, TeF_6, PoF_6
(1980)
Non-relativistic Hartree-Fock-Slater and relativistic Dirac-Slater self-consistent orbital models are applied for the analysis of the electronic structure of the chalcogen hexafluorides: SF_6, SeF_6, TeF_6 and PoF_6. The molecular eigenfunctions and eigenvalues are generated using the discrete variational method (DVM) with numerical basis functions. The results obtained for SF_6 are compared with other ab initio calculations. Information about relativistic level shifts and spin-orbit splitting has been obtained by ...
Aufsatz
State-dependent volume isotope shifts of low-lying states of group-IIa and -IIb elements
(1985)
Results of relativistic multiconfiguration Dirac-Fock calculations with an extended nucleus are used to analyze the volume isotope shifts of the resonance transitions in the group-IIa and -IIb elements
as well as in Yb. This is done together with a review of the isotope shift theory, including a critical evaluation and comparison of the semiempirical calculation of volume isotope shifts commonly
used today. Electronic factors F_i, proportional to differences of electronic densities over the nuclear volume, are ...
Aufsatz
Analysis of the electronic structure, hyperfine structure, and volume isotope shifts in the low lying states of BA I and BA II
(1988)
Relativistic multi-configuration Dirac Fock (MCDF) wavefunctions coupled to good angular momentum J have been calculated for low lying
states of Ba I and Ba II. These wavefunctions are compared with semiempirical
ones derived from experimental atomic energy levels. It is found that significantly better agreement is obtained when close configurations are included in the MCDF wavefunctions. Calculations of the electronic part of the field isotope shift lead to very good agreement with electronic factors
derived from ...
Aufsatz
Collision systems
(1984)
Various approximations which are possible for the theoretical description of colliding ion-atom systems are reviewed. With the emphasis on relativistic influences, a few comparisons of experimental results with relativistic calculations are made.
Aufsatz
Accurate Hartree-Fock-Slater calculations on small diatomic molecules with the finite-element method
(1988)
We report on the self-consistent field solution of the Hartree-Fock-Slater equations using the finite-element method for the three small diatomic molecules N_2, BH and CO as examples. The quality of the results is not only better by two orders of magnitude than the fully numerical finite difference method of Laaksonen et al. but the method also requires a smaller number of grid points.
Aufsatz
Study of 3d - 4f and 3d - 5f quartet and doublet transitions of doubly excited three-electron ions
(1989)
We present the first observation of optical transitions between doubly excited doublet states in the term systems N V, 0 VI and F VII. The spectra were produced by foil excitation of fast ion beams. The assignment of the spectral lines was made by comparison with the results of MCDP calculations along the isoelectronic sequence. The same method also led to the identification of two 3d - 4f quartet transitions in Mg X.