Core polarization effects

The magnetic parameters of aquo-Mb obtained from Fig. 44 are collected in Table 15.1. The theoretical A values for the heme and histidine nitrogen, which are about 50% smaller than the observed values, have been determined by Mun et al.242), using an extended Hiickel-type calculation. According to these authors, the agreement between theoretical and experimental values could perhaps be improved further by considering electron core polarization effects. 

Since core polarization effects are not included in the present DSW calculations, no Fermi contribution to the metal hyper-fine interaction arises from the present wavefunction, although its contribution to the experimental tensor is significant. We have discussed such core polarization effects elsewhere.O, )... 

In order to explicitly account for core-polarization effects in the calculation of oscillator strengths, a corrected transition operator is frequently employed in our calculations,... 

S. Mengali, R. Moccia, Non-empirical core polarization effects on the optical properties of Mg(I) I. discrete and continuum energy spectrum up to the third ionization threshold, J. Phys. B At. Mol. Opt. Phys. 29 (1996) 1597. 

Up to now,we always assumed a U coupled pair distribution to give a good description of both the proton 2p-2h excitation and of the neutron distribution over the valence model space.The quadrupole component of the proton-neutron force will induce 0+- 2+ pair breaking for both protons and neutrons which we call the core polarization effect.Thus,0 ground state and intruder wave functions... 

At present, the low-lying states of Na2 are better characterized computationally than experimentally, although multiphoton ionization experiments may change that picture eventually. We find reasonably close agreement between the results of our all-electron computations, pseudopotential (10), and model potential (11) computations. The latter two kinds of computations may give more accurate results than our ab initio computations since they may account for at least certain core polarization effects. 

Positive pair-binding energies, and hence the effective attractive interaction between electrons, arc necessarily a core polarization effect. If all of the 60 valence electrons were treated as an inert Fermi sea, the net interaction between two electrons added to a given molecule would necessarily be repulsive there is no bound-state solution to the Cooper problem with purely repttlsive interactions. It is the dynamic interactions with the valence electrons that are crucial in producing overscreening of the purely bare repulsive interaction. Although the first-order term does not involve any virtual excitations, the second-order theory includes important core-polarization effects. 

In the next fourth order, there appear diagrams, whose contribution into the ImA accounts for the core polarization effects. This contribution describes collective effects, and it is dependent upon the electromagnetic potential gauge (the gauge non-invariant contribution). Let us examine the multielectron atom with... 

Europium metal, like ytterbium at the end of the lanthanide series, loses only 2 electrons to the conduction band, and so retains a half filled 4f shell. Thus the observed C must be caused by core polarization effects i.e. since L 0, the magnetic field produced at the nucleus of the Eu ion is due mainly to polarization of electrons in closed shells by the spin moments of the 4f electrons. In the other rare earths this interaction is completely masked by the much larger field due to the orbital angular momentum of the 4f electrons. 

Here Im stands for the imaginary part, and e co) is the complex dielectric function. Using the experimental (o) for sodium [47] one obtains the absorption profile given as the last curve in Figure 5.10(d) (marked NaMie)- The calculated Mie resonance is narrower than the cluster plasmon peaks, but has nearly the same oscillator strength per electron. It has a maximum at Em c = 3.27 eV, which differs from the pure jellium result of 3.41 eV. The small but significant difference of 140 meV is attributed to core polarization effects, i.e. the... 

ECPs which substitute many electrons are much more prone to core polarization effects [805-807],... 

Preuss, Stoll, and co-workers at Stuttgart have employed several other ECP methods, which include core polarization effects in molecular calculations. The ECPs for all of the elements in the periodic table including lanthanides and actinides have been generated by these authors. They have also used these ECPs for computing the spectroscopic constants and potential energy curves of lanthanide oxides such as GdO, EuO, YbO, etc. 

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