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Title: Electric Double-Layer Structure in Primitive Model Electrolytes. Comparing Molecular Dynamics with Local-Density Approximations

We evaluate the accuracy of local-density approximations (LDAs) using explicit molecular dynamics simulations of binary electrolytes comprised of equisized ions in an implicit solvent. The Bikerman LDA, which considers ions to occupy a lattice, poorly captures excluded volume interactions between primitive model ions. Instead, LDAs based on the Carnahan–Starling (CS) hard-sphere equation of state capture simulated values of ideal and excess chemical potential profiles extremely well, as is the relationship between surface charge density and electrostatic potential. Excellent agreement between the EDL capacitances predicted by CS-LDAs and computed in molecular simulations is found even in systems where ion correlations drive strong density and free charge oscillations within the EDL, despite the inability of LDAs to capture the oscillations in the detailed EDL profiles.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [1]
  1. Univ. of California, Santa Barbara, CA (United States)
  2. (LLNL), Livermore, CA (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
1235740
Report Number(s):
LA-UR--14-28921
Journal ID: ISSN 0743-7463; TRN: US1600408
Grant/Contract Number:
AC52-07NA27344; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 31; Journal Issue: 11; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 25 ENERGY STORAGE; 36 MATERIALS SCIENCE Double layer; capacitance; electrolyte structure