Interfacial energy calculation of bcc/fcc interface

In order to explain the atomic arrangement of fcc metals with 1 ML thickness deposited on bcc(1 1 0) surface, such as Mo and W, the calculation of the interfacial energy between the fcc(1 1 1) monolayer and the bcc(1 1 0) surface was carried out using the Morse potential. Interactions of deposited fcc atoms with neighboring fcc atoms on the surface and with Mo atoms of the substrate within a constant distance were considered. First, the interfacial energy of the structure with a rigid fcc(1 1 1) monolayer on the substrate was calculated by varying the relative rotation angle and the atomic diameter ratio of bcc to fcc. The calculations showed that the energy minimum appears at Nishiyama–Wassermann and Kurdjumov–Sachs orientations at specific values of the atomic diameter ratio, which can be used to predict epitaxial orientation for various fcc/bcc combinations. Second, the calculations can interpret surface superstructures such as the 10×4 structure appearing in the Pb monolayer deposited on the Mo(1 1 0) surface with a coincident site lattice structure deformed slightly from the fcc(1 1 1) plane, as observed by RHEED experiment.