Stability, structural transformation, and reactivity ofGa13clusters

Abstract

First-principles pseudopotential calculations were performed to investigate the atomic structure, structural transformation, and reactivity of ${\mathrm{Ga}}_{13}$ clusters. ${\mathrm{Ga}}_{13}$ energetically favors a distorted decahedron. The decahedron is more stable than a relaxed icosahedron and a relaxed cuboctahedron by 0.22 and 0.67 eV, respectively. Structural transformations from the cuboctahedron and the icosahedron to the lowest-energy structure need to overcome barrier heights of less than 0.55 and 0.05 eV, respectively. Small activation energies are responsible for the flexibility and floppiness of ${\mathrm{Ga}}_{13}$ clusters. Reactions of the decahedral ${\mathrm{Ga}}_{13}$ cluster with Ga and As atoms induce structural changes of the substrate and produce cohesive-energy gains of 3.65 and 4.71 eV, respectively. Migrations of the Ga and As adatoms on the surface of the ${\mathrm{Ga}}_{13}$ cluster need to go over activation barriers with heights of less than 0.30 and 0.34 eV, respectively.