Regensburg 2000 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 17: POSTER I
DY 17.15: Poster
Montag, 27. März 2000, 15:00–18:00, D
Ion-ion correlations: an improved one-component plasma correction — •Marcia C. Barbosa1, Markus Deserno2, and Christian Holm2 — 1Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, 91501-970 Porto Alegre (RS), Brazil — 2MPI für Polymerforschung, Ackermannweg 10, 55128 Mainz
Based on a Debye-Hückel approach to the one-component plasma we propose a new free energy for incorporating ionic correlations into Poisson-Boltzmann like theories. Its derivation employs the exclusion of the charged background in the vicinity of the central ion, thereby yielding a thermodynamically stable free energy density, applicable within a local density approximation. This is an improvement over the existing Debye-Hückel plus hole theory, which in this situation suffers from a “structuring catastrophe”. For the simple example of a strongly charged stiff rod surrounded by its counterions we demonstrate that the Poisson-Boltzmann free energy functional augmented by our new correction accounts for the correlations present in this system when compared to molecular dynamics simulations.
[1] M. C. Barbosa, M. Deserno, and C. Holm, preprint cond-mat/9910364.