Magic clusters MAu_4 (M=Ti and Zr) and their dimers:How magic are they?

摘要

The stability of closed shell bimetallic magic clusters MAu_4 (M = Ti and Zr) is investigated theoretically through ab initio molecular orbital calculations.Both these clusters have tetrahedral structures and are found to be associated with large values of the ionization potential,HOMO-LUMO gap as well as the binding energies,which are characteristic of the magic clusters.However,the cluster-cluster interaction energy corresponding to a dimer formation is found to be unusually high (approx 5-7 eV) in contradiction to the usual properties of a magic cluster and is attributed to a 3-center-2-electron M-Au-M type bridge bonding as well as aurophilic attraction.Gross geometrical features of the individual clusters are,however,mostly retained in the dimer,thus satisfying the basic requirements for the cluster-assembled materials.This work would have important implications in the design of novel cluster-based nanomaterials for various nanoscale applications.