SMBp Group Meeting: Nikhil Agrawal (CCB)

Tuesday Jul 25, 2023, 2:00 PM → 3:00 PM America/New_York

3rd Floor Classroom/3-Flatiron Institute (162 5th Avenue)

Speaker: Nikhil Agrawal (CCB)

 

Topic: Beyond mean-field Poisson-Boltzmann: A self-consistent theory for electrical double layers

Abstract: An electrical double layer is an interface between a charged surface and a salt solution, and understanding its structure is crucial to explain numerous phenomena associated with soft matter and biophysics. While the classical mean-field Poisson-Boltzmann (PB) theory for electrical double layers is physically intuitive and numerically solvable, it has limitations. Specifically, it is applicable only to monovalent salts, low surface charges, low salt concentrations, and uniform dielectric media. These limitations arise from the neglect of three crucial factors: spatial correlations between ions, variable dielectric media, and the finite-size effects of ions and solvent molecules. Incorporating these factors is essential to explain many important phenomena such as vapor-liquid coexistence in ionic fluids, reversal of ionic current in charged nanochannels, attraction between like-charged surfaces, and repulsion between oppositely charged surfaces. In this talk, I will present a new theory titled "Gaussian Renormalized Fluctuation Theory" that addresses these limitations and provides a framework to model the aforementioned phenomena. This theory is self-consistent in the sense that it is derived from rigorous statistical mechanics and quantitatively captures experimental and simulation observations without relying on any phenomenological parameters.