Probing the electronic structures and properties of neutral and anionic ScSi(n)((0,-1)) (n = 1-6) clusters using ccCA-TM and G4 theory.

The geometries, electronic structures and energies of small ScSi n species (n = 1-6) and their anions have been systematically investigated by means of the higher level of the ccCA-TM, G4, and G4(MP2) schemes. The global minima of these clusters have been presented. The global minima of neutral ScSi n (n = 1-6) and their anions are "substitutional structure" which is derived from Si n+1 by replacing a Si atom with a Sc atom. The adiabatic electron affinities for ScSi n have been estimated. Compared with limited experimental data, the average absolute deviations from experiment for ccCA-TM, G4, and G4(MP2) are 0.21 eV, 0.22 eV, and 0.25 eV, respectively. The dissociation energies of Sc atom from the lowest-energy structure of ScSi n clusters have been evaluated to examine relative stabilities. The electron affinities and dissociation energies predicted by ccCA-TM, G4, and G4(MP2) methods, especially for ccCA-TM and G4, differ little from each other. The agreement may indicate they are reliable.