Model-free test of local-density mean-field behavior in electric double layers.
We derive a self-similarity criterion that must hold if a planar electric double layer (EDL) can be captured by a local-density approximation (LDA), without specifying any specific LDA. Our procedure generates a similarity coordinate from EDL profiles (measured or computed), and all LDA EDL profiles for a given electrolyte must collapse onto a master curve when plotted against this similarity coordinate. Noncollapsing profiles imply the inability of any LDA theory to capture EDLs in that electrolyte. We demonstrate our approach with molecular simulations, which reveal dilute electrolytes to collapse onto a single curve, and semidilute ions to collapse onto curves specific to each electrolyte, except where size-induced correlations arise.
Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA.
Brian
B
Giera
Neil
N
Henson
Edward M
EM
Kober
Todd M
TM
Squires
M Scott
MS
Shell