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 MgSi_n (n = 2–10) species and their anions have been systematically investigated at the highest level of Gaussian-3 (G3) theory. For neutral MgSi_n 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 MgSi_n 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 MgSi_n 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.