Particle-hole interaction

The above observation suggests an intriguing relationship between a bulk property of infinite nuclear matter and a surface property of finite systems. Here we want to point out that this correlation can be understood naturally in terms of the Landau-Migdal approach. To this end we consider a simple mean-field model (see, e.g., ref.[16]) with the Hamiltonian consisting of the single-particle mean field part Hq and the residual particle-hole interaction Hph-... 

In the Landau-Migdal approach the effective isovector particle-hole interaction Hph is given by... 

Several improvements to the original Kuo-Brown approach can be found in the literature [51], using either the partial summations of the folded diagrams as discussed above, or by including renormalized particle-hole interactions as advocated by the random-phase approximation or studying the perturbation expansion order by order in the interaction. Following the latter philosophy, Barrett and Kirson [52] showed that third-order contributions played a sizeable role. Typical examples of third-order topologies which play an important role are shown in Fig. 7. 

This irreducible e-h interaction, via a Ward identity, also determines the particle-hole interaction in the Bethe-Salpeter equation (2.7) for the two-particle propagator. Ideally, we should... 

A DIET process involves tliree steps (1) an initial electronic excitation, (2) an electronic rearrangement to fonn a repulsive state and (3) emission of a particle from the surface. The first step can be a direct excitation to an antibondmg state, but more frequently it is simply the removal of a bound electron. In the second step, the surface electronic structure rearranges itself to fonn a repulsive state. This rearrangement could be, for example, the decay of a valence band electron to fill a hole created in step (1). The repulsive state must have a sufficiently long lifetime that the products can desorb from the surface before the state decays. Finally, during the emission step, the particle can interact with the surface in ways that perturb its trajectory. 

Note that a dot ( ) always means a matrix element of the antisymmetrized electron interaction g, a cross (x) a matrix element of the one-particle operator /, while an open square ( ) collects the free labels in any of these contractions. If the reference function is a single Slater determinant, all cumulants X vanish one is then left with particle and hole contractions, like in traditional MBPT in the particle-hole picture. 

The relativistic or non-relativistic random-phase approximation (RRPA or RPA)t is a generalized self-consistent field procedure which may be derived making the Dirac/Hartree-Fock equations time-dependent. Therefore, the approach is often called time-dependent Dirac/Hartree-Fock. The name random phase comes from the original application of this method to very large systems where it was argued that terms due to interactions between many alternative pairs of excited particles, so-called two-particle-two-hole interactions ((2p-2h) see below) tend to... 

Absorption of the X-ray makes two particles in the solid the hole in the core level and the extra electron in the conduction band. After they are created, the hole and the electron can interact with each other, which is an exciton process. Many-body corrections to the one-electron picture, including relaxation of the valence electrons in response to the core-hole and excited-electron-core-hole interaction, alter the one-electron picture and play a role in some parts of the absorption spectrum. Mahan (179-181) has predicted enhanced absorption to occur over and above that of the one-electron theory near an edge on the basis of core-hole-electron interaction. Contributions of many-body effects are usually invoked in case unambiguous discrepancies between experiment and the one-electron model theory cannot be explained otherwise. Final-state effects may considerably alter the position and strength of features associated with the band structure. 

Charge transfer excitations simulated by quasi-particle techniques lack the electron-hole interaction (excitonic effect) because the two excess charges... 

Of the remaining ten nucleus-nucleus interaction diagrams, one involves a double de-excitation that is, the destruction of two nuclear particle-hole pairs, two diagrams involve a single de-excitation that is, the destruction of one nuclear particle-hole pair, four diagrams involve no change in the level of excitation, two diagrams involve... 

FOCI - first-order configuration interaction. Outer valence Green s function. Extended two-particle-hole Tamm-Dancoff approximation. 

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