Image force effects in the barrier height for metal-metal tunneling electrons

The density-functional theory is applied to calculate the interface barrier height between two metals as a function of the metal separation. Image-force effects are considered, since a nonlocal exchange-correlation energy functional is used. It is shown that the inclusion of nonlocality in the description of the exchange-correlation potential is important for a correct description of the barrier height, which turns out to be considerably lowered for metal-metal separations greater than a few angstroms.