LIMITATIONS OF MULTISTATE SOLVENT MODELS AT AN ELECTRODE ELECTROLYTE INTERFACE - A NUMERICAL STUDY USING THE BETHE APPROXIMATION/

The consequences of employing the Bethe approximation for dipolar inte ractions in the inner part of the electrical double layer are examined . Apart from providing explicit results for order parameters, dipolar potential, and differential capacitance for a two-state polarizable po int dipole model, a nonlinear regression analysis using experimental d ata is carried out in order to estimate interfacial constants such as permanent dipole moment, polarizability, effective coordination number , etc. This indicates that the simultaneous agreement of dipole potent ial and differential capacitance variations with charge density on the metal surface cannot be obtained using conventional discrete multista te orientational state models, thereby pointing to the need for explic it introduction of a metal surface into the double layer theories.