Michael J. Booth’s research while affiliated with University of Houston and other places

A study has been made of the electrical 'double layer' structure of molten salts, in particular a model of molten potassium chloride, using an integral equation approximation. This is in contrast to most statistical mechanical treatments of the double layer, which have concentrated on aqueous elecrolyte solutions. The results are compared with the output of computer simulations. In addition to the structural information contained in the density profiles, the calculations yielded charge profiles, the mean electrostatic potential and the double layer capacitance.

We present examples of the accurate, robust and efficient solution of Ornstein-Zernike type integral equations which describe the structure of both homogeneous and inhomogeneous fluids. In this work we use the Newton-GMRES algorithm as implemented in the public-domain nonlinear Krylov solvers NKSOL [P. Brown, Y. Saad, SIAM J. Sci. Stat. Comput. 11 (1990) 450] and NITSOL [M. Pernice, H.F. Walker, SIAM J. Sci. Comput. 19 (1998) 302]. We compare and contrast this method with more traditional approaches in the literature, using Picard iteration (successive-substitution) and hybrid Newton-Raphson and Picard methods, and a recent vector extrapolation method [H.H.H. Homeier, S. Rast, H. Krienke, Comput. Phys. Commun. 92 (1995) 188]. We find that both the performance and ease of implementation of these nonlinear solvers recommend them for the solution of this class of problem.

Following a systematic approximation to the Kirkwood—Green entropy expansion, within the grand canonical ensemble, functional optimization of the grand potential is used to derive closed sets of integral equations which approximate the structure and thermodynamics of both homogeneous and inhomogeneous fluids. Connections are made with existing approximations in the literature, and compact derivations are presented. Selected new equation sets are presented. The central role of the ‘ring’ term in the entropy expansion is emphasized.

The structure and thermodynamics of both 2--2 and 1--1 model electrolytes at a charged interface have been determined. The solvent is modeled as a structureless dielectric continuum. The structure is calculated from the `singlet ' version of the Ornstein-Zernike integral equation, using as input the structure of the bulk electrolyte from a recent integral equation theory. The approximation in the theory is the wall-ion bridge function, which is investigated for two levels of approximation. Surface thermodynamic quantities calculated from this structural information are compared with the classical Gouy-Chapman-Stern approximation for the interfacial region, computer simulations, and selected experimental data. Higher order structure predicted by the integral equations indicates that caution should be used when interpreting results of the classical approximation. Typeset using REVT E X I. THE ELECTRICAL DOUBLE LAYER Solutions invariably meet interfaces. The chemistry occurring at such ...

The structure and properties of an atom‐based model of water next to a planar interface are solved using an approximate integral equation theory. The input to the calculations is the structure of the bulk water in the form of the direct correlation functions. Predictions from the theory include the oxygen and hydrogen density profiles perpendicular to the interface, the mean electrostatic potential, the potential of zero charge, and the differential capacitance. The predicted structure is relatively insensitive to both the surface potential and the details of the short‐range wall–water potentials, and exhibits a layered structure which extends approximately 15 Å into the liquid. For our initial choice of the short‐range wall–water potential, we predict a value of −32 mV for the potential of zero charge and a differential capacitance of 4.89 μF cm−2 for pure water at a planar interface. The capacitance is apparently independent of the surface charge density and the surface potential.