Structural and homotop optimization of neutral Al-Si nanoclusters

The geometry and stability of aluminum-silicon alloys up to 13 atoms are investigated using electronic structure methods. The results agree well with available experimental data, while also predicting new potential candidates for detection. The exploration of the potential energy hypersurface of such particles is performed using both a thorough assessment of permutational isomers from selected structures and also using an unbiased genetic algorithm. It is shown that both approaches attain similar results for the specific cases analysed here. Several structures with non-magic number of electrons are shown to be very stable, such as Al4Si4, Al2Si6, Al2Si8, Al8Si4 and Al2Si11. A molecular orbitals analysis based in the spherical jellium model and deviations from it is performed for a better understanding of the properties of selected clusters.