Effects beyond the random-phase approximation in calculating the interaction between metal films

The performance of the adiabatic-connection fluctuation-dissipation theorem is discussed through the implementation of a non-local energy optimized exchange-correlation kernel to account for short-range correlation effects. We evaluate the jellium surface energy, through a painstaking extrapolation of single slab calculations, as well as the binding and interaction energies between two and three jellium slabs. Whereas total electron correlation energies are rather sensitive to the details of the kernel, any physically well-motivated approximation within our framework describes binding energies (including surface energies) within the same level of accuracy.