Benchmarking Orbital-Free Density-Potential Functional Theory of Electrified Metal-Solution Interfaces.

Area of Science:

• Computational chemistry
• Physical chemistry
• Materials science

Background:

• The electrical double layer (EDL) at metal-solution interfaces is crucial for electrochemical processes.
• Orbital-free density-functional theory (DFT) offers a computationally efficient method for modeling EDLs.
• The performance of orbital-free DFT for interfaces requires further investigation.

Purpose of the Study:

• To establish a benchmark for density-potential functional theory (DPFT) models of the EDL.
• To evaluate DPFT models using different kinetic energy functionals.
• To guide the development of orbital-free DFT for electrochemical interfaces.

Main Methods:

• Developed a constant-potential Kohn-Sham-Poisson-Boltzmann theory with exact kinetic energy as a benchmark.
• Solved Kohn-Sham and Poisson-Boltzmann equations self-consistently.
• Assessed DPFT models using Thomas-Fermi-von Weizsäcker (TFvW) and Pauli-Gaussian kinetic energy functionals.

Main Results:

• Obtained electron density, electrostatic potential, and double-layer capacitance for the EDL.
• TFvW kinetic energy functional generally outperformed the Pauli-Gaussian functional for EDL modeling.
• A reduced gradient coefficient in the TFvW functional is recommended for EDL modeling.

Conclusions:

• The study provides a benchmark for evaluating DPFT models of the EDL.
• TFvW functional with a modified gradient coefficient shows promise for accurate EDL simulations.
• Findings are critical for advancing orbital-free DFT in electrochemical interface research.