On the force between high‐density jellium‐metal surfaces at small separation

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Abstract
An exact relation is derived yielding the force constant of a bimetallic interface described by the jellium model in terms of the corresponding density‐potential response function. This relation in conjunction with a step‐density model and Thomas‐Fermi screening is used to derive an approximate formula for the force constant of a bimetallic interface in the limit of high densities. For identical metals it is demonstrated that the relation obtained satisfies the surface virial theorem and how the force between the two metal surfaces can be decomposed into the kinetic and interaction contributions. Starting from the small and large‐separation limiting behaviour of the force an attempt is made to estimate the adhesive energy of high density bimetallic contacts using the force constant calculated for the jellium model. For dissimilar metals it is found that the adhesive energy tend to a limit proportional to r1—5/4 r2—9/4 as r1, r2→ 0 and r1/r2→ 0, where r1 and r2 are the mean interelectronic distances of the two metals.