Starting with the general stress theorem as the dyadically generalized virial theorem, for metal-metal interfaces within the jellium approximation, a theorem is derived relating the interface stress, i.e., the density derivatives of the interfacial energy, to an appropriate integral of the momentum flux density (local stress or stress field). This interface stress theorem together with other sum rules are tested and illustrated by calculations using the gradient expansion method, i.e., the Thomas-Fermi method with corrections due to (i) exchange and correlation and (ii) gradient expansion both for the kinetic and the exchange and correlation energy. The results include the electron density, electric field, and stress field across the junction, as well as the interfacial energy, interfacial stress (with its parallel and perpendicular components), the adhesive force, and linear force constant for pairs of jellium densities corresponding to all alkali-metal interfaces.

• Received 2 April 1990

DOI:https://doi.org/10.1103/PhysRevB.41.10553