Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Intra-atomic polarization

To put it on a more quantitative basis, Johansson uses the expression for the critical point of the Mott transition as reformulated by Hubbard in terms of the bandwidth W[ and the polar state formation energy Uh (or effective intra-atomic correlation) (Eq. (36)). [Pg.43]

Recent work improved earlier results and considered the effects of electron correlation and vibrational averaging [278], Especially the effects of intra-atomic correlation, which were seen to be significant for rare-gas pairs, have been studied for H2-He pairs and compared with interatomic electron correlation the contributions due to intra- and interatomic correlation are of opposite sign. Localized SCF orbitals were used again to reduce the basis set superposition error. Special care was taken to assure that the supermolecular wavefunctions separate correctly for R —> oo into a product of correlated H2 wavefunctions, and a correlated as well as polarized He wavefunction. At the Cl level, all atomic and molecular properties (polarizability, quadrupole moment) were found to be in agreement with the accurate values to within 1%. Various extensions of the basis set have resulted in variations of the induced dipole moment of less than 1% [279], Table 4.5 shows the computed dipole components, px, pz, as functions of separation, R, orientation (0°, 90°, 45° relative to the internuclear axis), and three vibrational spacings r, in 10-6 a.u. of dipole strength [279]. [Pg.165]

Eq, (4-12), as applied to hybrid states, is used in the last step it shows also that = 0. The remarkable result is that the matrix elements are not expected to vary with polarity in an isoelectronic scries. This feature also applies to the intra-atomic terms in the matrix element between bonding and antibonding orbitals on adjacent sites. A similar treatment of the matrix elements ofx indicates that they vary inversely with covalcncy 1 isoelectronic... [Pg.102]

Stood. As an example, the interplay of spin-orbit interaction and electron correlations is still a much debated problem. The interplay of orbital polarization and correlation including diamagnetism is still far from being solved. Also, the influence of intra-atomic non-collinearity of the magnetization density on observable properties is not so clear till now [73]. [Pg.773]

Here I(Q) is the X-ray interference function, representing the wave number dependence of the X-ray intensity after dividing by the squared structure factor f(Q) in order to remove the <2 d P > d nce due to intra-atomic interference effects. The function I(Q) has also been corrected for by several other structure-independent quantities such as polarization, absorption and geometrical factors. [Pg.302]

EuO was the first ferromagnetic semiconductor found in the compounds of the lanthanide elements. There are several surprises associated with this unusual material. One of these is how can EuO be ferromagnetic (T = 77 K) without any conduction electrons, i.e. the RKKY exchange mechanism cannot account for this ferromagnetism. The current model is based on a cation-cation superexchange mechanism in which a 4f electron of one europium ion is transferred to 5d state of a next nearest (nn) europium ion, which then polarizes the 4f spin of the nn europium ion via an intra atomic f-d exchange (Wachter 1979). [Pg.467]

For a ferromagnetic nanosolid, the magnetic moment at very low temperature increases with the inverse of size compared with the bulk value due to the deepening of the intra-atomic potential well that entraps and polarizes the surface spins contributing to the angular momentum of the under coordinated atoms of a nanosohd. [Pg.396]

So far we have considered the optical properties of surfaces and interfaces under the assumption that the amplitude of the incident light wave, E,-, is negligible in comparison with the intra-atomic field strengths and hence the electric displacement vector is a linear function of E, (see Eq. (3.63)). For larger amplitudes the polarization which is induced by the light wave can be quite generally written in the form of a power series... [Pg.139]

Optimization of the valence and dihedral angles yields planar cyclic structures for the 3- to 5-ring intermediates in contrast to a chair conformation for that of the 6-ring. In the cases of n = 4, 5, 6 the oxygen atom is placed almost in the plane of the three C-atoms directly bonded to it. Therefore, an intramolecular solvation of the cationic chain end by methoxy groups which are bonded to the polymer backbone is preferred in the gas phase. The calculations show that for a non-polar solvent such as CH2C12 a decrease in stability of the cyclic intermediates exists. But this decrease does not result in a total break of the intramolecular solvation (Table 13). An equilibrium between open chain and cyclic intermediates must only be taken into account in more polar solvents, due to the competition of intra- and intermolecular solvation. [Pg.206]

Thus Dr. Burawoy s statement that our calculations are based on the assumption that the A—H bond is mainly ionic, appears to be erroneous. The hydrogen bond energy equation (3) (page 386 of my paper) is based on general considerations and is valid for the interaction of B both with the homopolar (A—X) and with the Ionic molecule (A X+) and elucidates the process of interaction of the polar molecule with an atom and the role played by hydrogen in the formation of inter- (end intra-) molecular bonds. Contrary to Burawoy s statement equation (3) certainly takes into account the repulsion, between H and B. [Pg.391]


See other pages where Intra-atomic polarization is mentioned: [Pg.75]    [Pg.158]    [Pg.75]    [Pg.158]    [Pg.112]    [Pg.387]    [Pg.199]    [Pg.36]    [Pg.41]    [Pg.528]    [Pg.1]    [Pg.103]    [Pg.44]    [Pg.50]    [Pg.99]    [Pg.71]    [Pg.187]    [Pg.52]    [Pg.73]    [Pg.78]    [Pg.112]    [Pg.213]    [Pg.119]    [Pg.229]    [Pg.178]    [Pg.38]    [Pg.910]    [Pg.317]    [Pg.207]    [Pg.112]    [Pg.221]    [Pg.222]    [Pg.541]    [Pg.215]    [Pg.338]    [Pg.635]    [Pg.329]    [Pg.107]    [Pg.119]    [Pg.457]   
See also in sourсe #XX -- [ Pg.73 , Pg.74 ]




SEARCH



Polar atoms

Polarization atomic

Polarization, atoms

Polarized Atoms

© 2024 chempedia.info