Density functional B3LYP/LANL2DZ and B3LYP/6-31G* calculations have been carried out to study the structure and stability of model Gan(n + )/2Sin(n - 1)/2H3n + n(n - 1)/2 and Gan(n + 1)/2Sin(n-1)/2(SiH3)(3n)Hn(n - 1)/2 clusters (n 2, 3, and 4). The clusters are thermodynamicaly stable, have a triangular shape, and consist of fused non-planar Ga3Si3 hexagons with three external Si-Ga bonds in the triangle vertices. The Si-Ga bond strength in the clusters is estimated as 40-42 kcal/mol. The model clusters simulate the two-dimensional Ga-induced triangular magic clusters on the Si(111) surface recently observed experimentally. The cluster growth process is predicted to be exothermic.