We evaluate the electrostatic interaction energy between two surfaces, one flat and the other slightly curved, in terms of the two-point autocorrelation functions for patch potentials on each one of them, and of a single function $\psi$ which defines the curved surface. The resulting interaction energy, a functional of $\psi$, is evaluated up to the second order in a derivative expansion approach. We derive explicit formulas for the coefficients of that expansion as simple integrals involving the autocorrelation functions, and evaluate them for some relevant patch-potential profiles and geometries.

• Received 17 September 2013

DOI:https://doi.org/10.1103/PhysRevA.88.062501