Year: 2005
Type: article
Abstract: Simulations of the Lebowitz length, ${\ensuremath{\xi}}_{\mathrm{L}}(T,\ensuremath{\rho})$, are reported for the restricted primitive model hard-core (diameter $a$) $1\ensuremath{\mathbin:}1$ electrolyte for densities $\ensuremath{\rho}\ensuremath{\lesssim}4{\ensuremath{\rho}}_{c}$ and ${T}_{c}\ensuremath{\lesssim}T\ensuremath{\lesssim}40{T}_{c}$. Finite-size effects are elucidated for the charge fluctuations in various subdomains that serve to evaluate ${\ensuremath{\xi}}_{\mathrm{L}}$. On extrapolation to the bulk limit for $T\ensuremath{\gtrsim}10{T}_{c}$ the exact low-density expansions are seen to fail badly when $\ensuremath{\rho}>\frac{1}{10}{\ensuremath{\rho}}_{c}$ (with ${\ensuremath{\rho}}_{c}{a}^{3}\ensuremath{\simeq}0.08$). At higher densities ${\ensuremath{\xi}}_{\mathrm{L}}$ rises above the Debye length, ${\ensuremath{\xi}}_{\mathrm{D}}\ensuremath{\propto}\sqrt{T/\ensuremath{\rho}}$, by 10%--30% (up to $\ensuremath{\rho}\ensuremath{\simeq}1.3{\ensuremath{\rho}}_{c}$); the variation is portrayed fairly well by the generalized Debye-H\"uckel theory. On approaching criticality at fixed $\ensuremath{\rho}$ or fixed $T$, ${\ensuremath{\xi}}_{\mathrm{L}}(T,\ensuremath{\rho})$ remains finite with ${\ensuremath{\xi}}_{\mathrm{L}}^{c}\ensuremath{\simeq}0.30a\ensuremath{\simeq}1.3{\ensuremath{\xi}}_{\mathrm{D}}^{c}$ but displays a weak entropylike singularity.
Source: Physical Review Letters
Authors: Young C. Kim, Erik Luijten, Michael E. Fisher
Institution: University of Maryland, College Park
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2066738953