Variational functional in local density approximation for coulombic electrolyte correlations in the electric double...

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Conventional mean-field theories often neglect crucial correlations between electrolyte ions and solvent dipoles.
• Accurate modeling of electrolyte solutions is vital for understanding phenomena like solvation and screening.
• Interfacial capacitance at metal-electrolyte interfaces is a key property influenced by these correlations.

Purpose of the Study:

• To derive a first-principles coulombic correlation functional for electrolyte solutions.
• To incorporate ion-dipole correlations, including screening and solvation effects, into theoretical models.
• To evaluate the functional's performance in describing metal-electrolyte interfaces.

Main Methods:

• Derivation of a one-loop (1L) and local-density-approximation (LDA) coulombic correlation functional from a many-body partition function.
• Parameterization of the 1L-LDA functional using experimental dielectric permittivity and activity coefficients.
• Embedding the 1L-LDA functional into a combined quantum-classical model for interface simulations.

Main Results:

• The 1L-LDA functional successfully captures ion-dipole correlations, improving upon mean-field approximations.
• The functional was tuned using bulk electrolyte properties, demonstrating its adaptability.
• Simulations of metal-electrolyte interfaces revealed a more pronounced double-peak structure in interfacial capacitance, with higher peaks and shorter separation.

Conclusions:

• The developed 1L-LDA functional provides a more accurate description of electrolyte solutions and interfaces.
• Electrolyte correlation effects significantly impact the capacitive response at metal-electrolyte interfaces.
• The improved agreement with experimental data validates the importance of including these correlation effects.