Study on structures and electronic properties of neutral and charged MgSin- (n=2-10) clusters with a Gaussian-3 theory

The equilibrium geometries, energies, charge transfer, and dipole moments of small MgSin (n = 2-10) species and their anions have been systematically investigated at the highest level of Gaussian-3 (G3) theory. For neutral MgSin clusters, the ground-state structures are found to be "attaching structure" in which the Mg atom is bound to Si-n clusters. The lowest-energy structures for their anions, however, are found to be "substitutional structures", which are derived from Si(n+1)by replacing a Si atom with a Mg atom. The reliable adiabatic electron affinities of MgSin have been predicted to be 1.84 eV for MgSi2, 1.90 eV for MgSi3, 2.17 eV for MgSi4, 2.35 eV for MgSi5, 2.45 eV for MgSi6, 2.18 eV for MgSi7, 2.98 eV for MgSi8, 3.00 eV for MgSi9, and 2.00 eV for MgSi10. The dissociation energies of Mg atom from the lowest-energy structure of MgSin clusters have been evaluated to examine relative stabilities. The charge transfer and dipole moments have also been calculated to further understand the interaction between the Mg atom and the silicon clusters. (C) 2010 Elsevier B.V. All rights reserved.