## Search

Now showing items 31-40 of 44

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Aufsatz
Many electron coupled channel calculations for the system F{^8+} - Ne

(1989)

To describe the time dependence of an atomic
collision system the Dirac equation usually is rewritten in a coupled channel equation. We first discuss part of the approximation used in this approach and the connection of
the many particle with the one particle interpretation. The coupled channel equations are solved for the system F{^8+} - Ne using static selfconsistent many electron Dirac-Fock-Slater wavefunctions as basis. The resulting P(b) curves for the creation of a Ne K-hole are in reasonable agreement with ...

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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 ...

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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 ...

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Aufsatz
Estimation of the ground state correlation energy for isoelectronic series of 2 to 20 electrons

(1987)

Correlation energies for all isoelectronic sequences of 2 to 20 electrons and Z = 2 to
25 are obtained by taking differences between theoretical total energies of Dirac-Fock
calculations and experimental total energies. These are pure relativistic correlation energies because relativistic and QED effects are already taken care of. The theoretical as
well as the experimental values are analysed critically in order to get values as accurate
as possible. The correlation energies obtained show an essentially consistent ...

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Aufsatz
Test for basis-set errors in relativistic Dirac-Fock-Slater calculations with a numerical AO-DFS-basis

(1987)

A fully relativistic four-component Dirac-Fock-Slater program for diatomics,
with numerically given AO's as basis functions is presented. We discuss the problem of the errors due to the finite basis-set, and due to the influence of the negative energy solutions of the Dirac Hamiltonian. The negative continuum contributions are found to be very small.

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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.

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Aufsatz
Relativistic Dirac-Fock-Slater program to calculate potential-energy curves for diatomic molecules

(1986)

A LCAO-MO (linear combination of atomic orbitals - molecular orbitals) relativistic Dirac-Fock-Slater program is presented, which allows one to calculate accurate total energies for diatomic molecules.
Numerical atomic Dirac-Fock-Slater wave functions are used as basis functions. All integrations as well as the solution of the Poisson equation are done fully numerical, with a relative accuracy of 10{^-5} - 10{^-6}. The details of the method as well as first results are presented here.

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Aufsatz
An attempt on the calculation of relativistic potential energy curves: noble gas difluorides

(1980)

Total energy SCF calculations were performed for noble gas difluorides in a relativistic
procedure and compared with analogous non-relativistic calculations. The discrete
variational method with numerical basis functions was used. Rather smooth potential
energy curves could be obtained. The theoretical Kr - F and Xe - F bond distances were calculated to be 3.5 a.u. and 3.6 a.u. which should be compared with the experimental values of 3.54 a.u. and 3.7 a.u. Although the dissociation energies are off by a factor of ...

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Aufsatz
Comparison between experiment and theory in heavy electronic systems

(Gräff, G. (Hrsg.), 1981)

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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.