TMGe8-17- (TM = Ti, Zr, Hf, V, Nb, Ta) clusters: group determined properties

Germanium cluster anions doped with transition metal (TM) atoms from groups 4 and 5, TMGe8-17- (TM = Ti, Zr, Hf, V, Nb, Ta), have been computationally investigated. Low-lying energy isomers of these clusters were found through a genetic algorithm coupled with density functional theory. The photoelectron spectra were simulated accordingly which reproduce well the measured spectra, indicating the proper identification of the ground-state structures. In these clusters, the TM atoms tend to be surrounded by Ge atoms, and the structures begin to change from exo- to endohedral at n = 9. From n = 10 the endohedral structures start to build up, and at n = 14, the complete close-cage is formed. The 4th and 5th group TM doped clusters share the same geometric structure (except for sizes 10 and 12 for 4th group) and own very similar bonding and electronic properties, especially for the 2nd and the 3rd rows. It is also shown that the larger the atomic number of TM, the greater the binding energy of the Ge clusters doped with TM from the same group. The complete closed cage structure shows high stability, i.e., TMGe14- (TM = V, Nb, Ta) clusters have closed electronic shells with very high stability. They satisfy the 18-electron rule, which make them superatom clusters, and may be suitable as building blocks for novel nanomaterials.