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Göteborgs universitets publikationer

Screened Coulomb potential and the renormalized charges of ions and molecules in electrolyte solutions

Författare och institution:
Roland Kjellander (Institutionen för kemi); Rosa Ramirez (-)
Publicerad i:
Journal of Physics-Condensed Matter, 17 ( 45 ) s. S3409-S3421
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
We consider solutions that consist of solute and solvent molecules of arbitrary sizes, shapes and internal charge distributions. The free energy of interaction (the potential of mean force) between the molecules is analysed in terms of a screened Coulomb potential and renormalized charge distributions of the molecules. The emphasis in this work is to bring out a simple physical interpretation of the theory, but the treatment is based on exact statistical mechanical theory without any approximations. The results thereby are the true properties of the system for given pair interaction potentials between the constituent particles. In general, the electric potential from any molecule in the solution can be exactly obtained for all distances by using a (generalized) screened Coulomb potential, provided the source charges constitute a renormalized charge distribution of the molecule. When charge renormalization is done consistently, macroions, small ions and solvent molecules are treated in fundamentally the same manner and all particles acquire renormalized charge distributions that generally are different from their actual (bare) distributions. The electrostatic free energy of interaction is given by the interaction between the renormalized charge distributions of the molecules as mediated by the screened Coulomb potential. The exact formalism is also used for the primitive model of electrolytes. The concepts in the general theory are illustrated by expressing the Poisson-Boltzmann and hypernetted chain (HNC) approximations in this alternative framework. Conditions are given under which the exact theory predicts the existence of attractive electrostatic interaction between two identical particles at large distances from each other.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Kemi ->
Fysikalisk kemi
Postens nummer:
Posten skapad:
2007-10-24 13:15

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