Global geometry optimization of silicon clusters described by three empirical potentials

The “basic-hopping” global optimization technique developed by Wales and Doye is employed to study the global minima of silicon clusters Sin (3\u3cnnnn=17, as opposed to n=19. For larger SW clusters (20\u3cn n =20. In particular, the overall structural features of SW Si21, Si23, Si25, and Si28 are nearly identical to the MSW counterparts. With the SW Si21 as the starting structure, a geometric optimization at the B3LYP/6-31G(d) level of density-functional theory yields an isomer similar to the ground-stateisomer of Si21 reported by Pederson et al. [Phys. Rev. B 54, 2863 (1996)]