1. In 1980, Stigter extended Booth's model to allow for higher surface potentials . 2. We see that the surface potential has a direct relationship with the temperature. 3. This involves the equations being solved with simple boundary conditions such as constant surface potential . 4. Electric potential difference between the fluid bulk and the surface is called the electric surface potential . 5. Surface functionalization can largely change the surface potential . 6. As a result, the Hamiltonian is a quadratic functional of the surface potential " ? ". 7. The properties of this ion are strongly related to the surface potential present on a corresponding solid. 8. And the corresponding equation for the free-surface potential is identical, with \ zeta replaced by \ varphi. 9. If the partition function has no special surface potential terms, this is the surface of a hard solid. 10. Accounting for non-Coulombic interactions increases the ion concentration at the surface and leads to a reduced surface potential .