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Now showing items 171-180 of 209
Aufsatz
Unrestricted hartree-fock calculation of the ionization potential of small Hg_n clusters
(1993)
The ionization potential of small Hg_n clusters has been calculated. For the first time good agreement with experimental results has been obtained. It is shown that interatomic Coulomb interactions are important. The energy of Hg_n^+ is calculated using the unrestricted inhomogeneous Hartree-Fock approximation. As a consequence of a change in the charge distribution in Hg_n^+ , we obtain an abrupt change in the slope of the ionization potential at the critical cluster size n_cr ~ 14. The presented results are expected ...
Aufsatz
Calculation of the electronic properties of neutral and ionized divalent-metal clusters
(1993)
The electronic properties of neutral and ionized divalent-metal clusters have been studied using a microscopic theory, which takes into account the interplay between van der Waals (vdW) and covalent bonding in the neutral clusters, and the competition between hole delocalization and polarization energy in the ionized clusters. By calculating the ground-state energies of neutral and ionized. Hg_n clusters, we determine the size dependence of the bond character and the ionization potential I_p(n). For neutral Hg_n ...
Aufsatz
On the transition from localized to delocalized electronic states in divalent-metal clusters
(1991)
The transition from van der Waals to covalent bonding, which is expected to occur in divalent-metal clusters with increasing cluster size, is discussed. We propose a model which takes into account, within the same electronic theory, the three main competing contributions, namely the kinetic energy of the electrons, the Coulomb interactions between electrons, and the s \gdw p intraatomic transitions responsible for van der Waals like bonding. The model is solved by taking into account electron correlations using a ...
Aufsatz
Two-muonic atoms
(1974)
X-ray transition energies for two-muonic atoms are calculated. The basis are relativistic self-consistent-field calculations including the corrections normally known in muonic atoms plus the vacuum polarization, magnetic interaction and retardation in the \mu-\mu-interaction, the specific mass correction and the configuration interaction.
Aufsatz
Femtosecond probing of sodium cluster ion Na_n ^+ fragmentation
(1992)
We report on the first femtosecond time-resolved experiments in cluster physics. The photofragmentation
dynamics of small sodium cluster ions Na_n ^+ have been studied with pump-probe techniques. Ultrashort
laser pulses of 60-fs duration are employed to photoionize the sodium clusters and to probe the
photofragments. We find that the ejection of neutral dimer Na_2 and, observed for the first time, neutral
trimer Na_3 photofragments occur on ultrashort time scales of 2.5 and 0.4 ps, respectively. This and the
absence ...
Aufsatz
Model calculations on the influence of quantum electrodynamical effects on the chemistry of superheavy elements.
(1972)
Using a phenomenological model, the influence of quantum electrodynamical effects on the prediction of the chemical behavior of superheavy elements within a relativistic Dirac-Slater calculation was investigated. This influence will be small and nondetectable for elements up to Z = 114. For elements near Z = 164 some changes in the ground state configurations occur but the chemical behavior will not change. Using this heuristic model, it is also possible to calculate elements beyond Z = 175. As an example we have ...
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.
Aufsatz
Effect of nuclear motion on the energy eigenvalues in muonic atoms
(1973)
I have investigated the effect of the nuclear motion on the energy eigenvalues in muonic
atoms. In addition to the usually used reduced-mass correction, I have calculated the relativistic influences including the magnetic and retardation interaction between the nucleus and the muon for the inner orbitals of muonic atoms.