A combined LEED and DFT surface structure determination of Cu3Au(001): Evidence of a surface stacking fault

In this work, we have investigated the surface structure of Cu3Au(001) using low energy electron diffraction analysis and ab initio calculations by density functional theory. Our results indicate a different structure from that usually reported in the literature, where we have observed a stacking fault between the first and third layers of the surface. The rippling effect and the interlayer distances belonging to the first six layers of the surface were calculated and compared with other works too. Specifically, a rippling with gold atoms moving towards the vacuum in the first layer of 0.09 Å was observed and of 0.02 Å in the third layer. A small expansion of the first interlayer distance of 1.3% and a contraction of 0.8% at the second also were observed. Finally, ab initio calculations performed in this work are in good agreement with the experimental results.