Coulomb screening

Giese TJ, York DM (2004) Many-body force field models based solely on pairwise Coulomb screening do not simultaneously reproduce correct gas-phase and condensed-phase polarizability limits. J... 

The role of the non-equilibrium charge screening is emphasized by calculations neglecting such screening, i.e., when equations (5.1.54) are omitted and Uv r) — L/r is postulated. In this case mutual repulsion of similar particles accompanied by the attraction between dissimilar particles are characterized by the infinite interaction radius between particles which leads immediately to the Coulomb catastrophe - an infinite increase in K(t) in time shown in Fig. 6.47. This effect is independent of the choice of the initial defect distributions for both similar and dissimilar particles. On the other hand, incorporation of the Coulomb screening makes equations (6.4.1), (6.4.2) asymptotically valid for any initial distribution of particles. 

As can be seen, the theoretical results are not in agreement with the experimental values. Here we have first calculated the Coulomb screening parameters... 

In this paper, we investigate the correction terms obtained when applying a covariant Pauli-Villars regulator [16] when formulating the PWR procedure. In Section II we consider the first-order self energy and the Coulomb screened self energy is discussed in Section III. Finally, we derive an expression suitable for numerical evaluation of the correction term in the Coulomb screened case. 

We will show below that this correction term vanishes for the first-order self energy and cancels for the Coulomb-screened self energy. This is, however, not always the case for higher-order effects. As an example, for the self energy in an external magnetic potential the correction term gives rise to a finite shift... 

In the partial-wave renormalization approach, which we consider in this paper, we have shown that these correction terms vanish for the first-order selfenergy and also for Coulomb screened self-energy. However, in the last case we obtain non-zero correction terms for the different subgroups of diagrams,... 

Polarization of ions can be included in one of two ways. The natural approach is to use point ion polarizabilities, which has been successfully explored by Wilson and Madden (1996). An alternative, which has been used for many decades, is the so-called shell model (Dick and Overhauser 1958) as illustrated schematically in Figure 1. This is a simple mechanical model, in which an ion is represented by two particles-a core and a shell-where the core can be regarded as the representing the nucleus and inner electrons, while the shell represents the valence electrons. As such, all the mass is assigned to the core, while the total ion charge (qt = qc + qs) is split between both of the species. The core and shell interact by a harmonic spring constant, Kcs, but are Coulombically screened from each other. The polarizability is then given by ... 

J. N. Chazalviel, Coulomb Screening by Mobile Charges, Birkhauser, Boston, 1999. 

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