Theory of the bimetallic interface

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Abstract
The self-consistent electronic structure and adhesive energetics are computed for contacts between all combinations of Al(111), Zn(0001), Mg(0001), and Na(110). The electronic structure is quite different from that of contacts between identical metals, with large electronic potential barriers appearing even at the smallest separations. Charge transfer and/or rearrangement distributions are plotted for various contact separations. These density differences lead to potential differences, or changes in the electronic potential distributions in the interfaces due to charge transfer and/or rearrangement. They have little relation to the contact potential, and vary rapidly with contact interfacial separation. The kinetic energy initiates the bond, while the exchange-correlation energy is the dominant contributor to the strength of the adhesive bond. The range of strong bonding is about 0.2 nm. Electronic barrier heights saturate more slowly with contact separation. One can expect metallic transfer for the contacts involving Na, but it is less likely for the others. A universal adhesive energy relation was found to accurately describe the energetics of all ten bimetallic interfaces considered here. Because of this universality, one can expect to determine the energetics of other bimetallic interfaces via a simple scaling of the universal relation. A close relationship is revealed between diatomic molecular bonds and bonds across a bimetallic interface.