Interactions, collective Coulomb short-range

The collective excitations may decay in a number of ways. In an electron gas they decay owing to the interaction between electrons. In this case the Coulomb interaction of electrons is strongly screened by the electron cloud and is noticeable only at short distance. Owing to this short-range interaction, the oscillational energy of a plasmon transforms into kinetic energy of individual electrons, that is it is distributed all over the electron gas.1... 

Real proteins are built up both from hydrophobic and polar amino acid residues, some of the latter can be charged. Many of the conformational and collective properties of proteins are due to a complex interplay between short-range (hydrophobic) effects and long-range (Coulomb) interactions. Electrostatic effects can also determine some of the unique solution properties of globular proteins. We have already discussed the results of simulations... 

If you had substituted any attractive short-ranged potential (one that falls off more rapidly than r ) into Equation (24.17), it would have led to the pressure p oc y- , just as in Equation (24.22). For this reason, many different types of interaction are collectively called van der Waals forces. They all lead to the same contribution to p(V). For longer-ranged forces, such as coulombic interactions, the integral in Equation (24.17) becomes inhnite, and Equation (24.20) w ould not apply. For long-range interactions, you need to resort to the methods of Chapters 20 to 23, such as the Poisson equation. 

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