Vibrations of tetrahedral Co and Cu clusters on a Cu(111) surface

Vibrational properties of tetrahedral clusters of Cu and Co on the Cu(111) surface are studied by using interatomic interaction potentials constructed within tight‐binding second moment approximation. It was shown that interaction of the Co 4 and Cu 4 clusters with the substrate leads to arising of frustrated translation and frustrated rotation in‐plane polarized vibrational modes localized on the cluster atoms. The vibrational modes of the free Cu 4 cluster upon its adsorption on the Cu(111) surface mix with Cu bulk phonons and become almost delocalized. Contrary to that, in the Co 4 cluster on the surface the high frequency modes remain strongly localized and mixed with the nearest neighbor atoms vibrations. The highest frequency vibration of the Co 4 cluster splits due to different interaction with certain groups of nearest neighbor atoms (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)