Function-Space-Based Solution Scheme for the Size-Modified Poisson-Boltzmann Equation in Full-Potential DFT.

Area of Science:

• Computational chemistry
• Physical chemistry
• Theoretical chemistry

Background:

• The size-modified Poisson-Boltzmann (MPB) equation is a key implicit solvation model.
• Accurately modeling electrolytic solvent effects and finite-sized ions is crucial.
• Existing methods may not fully leverage specialized computational resources.

Purpose of the Study:

• To present a general and efficient solution scheme for the MPB equation.
• To implement this scheme within the full-potential density-functional theory (DFT) code FHI-aims.
• To validate the DFT+MPB approach for describing aqueous salt solutions.

Main Methods:

• Utilizing a fast function-space-oriented Newton method.
• Employing a Green's function preconditioned iterative linear solver.
• Integrating specialized integration grids and optimized schemes for numerical efficiency.

Main Results:

• The DFT+MPB approach, with Stern layer correction, accurately describes KCl aqueous solution activity coefficients across concentrations.
• The method demonstrates high sensitivity to ionic parameters.
• Successful implementation in the FHI-aims DFT code.

Conclusions:

• The developed DFT+MPB method offers an efficient and accurate way to model solvation and electrolyte effects.
• Experimental activity coefficient data is valuable for systematic parameterization of ionic models.
• This work advances computational modeling for electrolyte solutions in chemistry and materials science.