Coulombic energy, gain

The conditions for the ion pair formation can be easily realized in the following way. Each counterion can dther be free or form an ion pair with the co-ion. In the latter case, there is some gain in the energy of Coulomb attraaion between the ions in the pair and some loss in the translational entropy of the counterion. If a is the distance between the ions in the ion pair, fi the dielectric constant of the medium, and e an elementary charge, the Coulomb energy gain resulting from the formation of an ion pair from monovalent ions is... 

Coulomb correlation energy, U. The energy gain due to band formation is of the order of the bandwidth, W. Provided U can be calculated Table 1 can be used to examine the criterion UAV = 1 for Mott-localization ... 

For proteins with comparable surface hydrophobicity, the adsorption uptake correlates strongly with the extent of protein under-wrapping [19]. As an adequate control, only proteins with the same extent of surface hydrophobicity or solvent-exposed nonpolar area were included in the comparative analysis. Hence, the attractive drag exerted by dehydrons on test hydrophobes became accessible. The net gain in Coulomb energy associated with wrapping a dehydron has been experimentally determined to be 4 kJ/mol [19]. The adhesive force exerted by a dehydron on a hydrophobe at 6 A distance is 7.8 pN, a magnitude comparable to the hydrophobic attraction between two nonpolar moieties that frame unfavorable interfaces with water. 

In the SI (or MKS) system of units, the joule (J) is a unit of energy, but the electron-volt (eV) is the traditional unit used in ion-solid interactions we can define 1 eV as the kinetic energy gained by an electron accelerated through a potential difference of 1 V. The charge on the electron is 1.602 x 10 19 C, and a joule is a Coulomb-volt, so that the relationship between these units is given by... 

Note that based on the Pauli exclusion principle, this is not applicable to electron pairs with the same quantum numbers except that of spin. This indicates that the wavefunction E is considered to have a hole at rn = 0, which is called a Coulomb hole. By excluding close electrons, this Coulomb hole decreases the Coulomb interactions, thus lowering the total energies. This energy gain corresponds to the electron correlation. 

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