KCS

We performed density functional calculations to examine the self-intermolecular interaction of metal tetraauride MAu₄ (M = Ti, Zr, and Hf) clusters. The ground-state structure of the metal auride clusters can be described as a (μ-Au)₃ bridged structure (C_s) with higher binding energy and larger HOMO-LUMO gap than the well-known (μ-Au)₄ D_2d form. The C_s structure is very similar to the ground-state structure of TiH₄ dimer. The (MAu₄)₂ clusters also have similar bonding nature, three center two electron (3c-2e) bonding, to (TiH₄)₂. The binding energy of TiAu₄ dimer is 3.06 eV, which is larger than 2.21 eV for the TiH₄ dimer. Bonding energy decomposition analysis confirmed that the favorable orbital interaction between occupied Au(6s) and unoccupied Ti(3d) orbitals leads to the strong dimeric interaction for TiAu₄ dimer. Our calculations clearly show the hydrogen-like behavior of gold atom in the metal auride complexes.