Published Research - Department of Chemistry

 

Date of this Version

July 2003

Comments

Published by American Institute of Physics. J. Chem. Physics VOLUME 119, NUMBER 3, 15 JULY 2003. ©2003 American Institute of Physics. Permission to use. http://jcp.aip.org/.

Abstract

The “basic-hopping” global optimization technique developed by Wales and Doye is employed to study the global minima of silicon clusters Sin (3<n<30) with three empirical potentials: the Stillinger–Weber (SW), the modified Stillinger–Weber (MSW), and the Gong potentials. For the small-sized SW and Gong clusters (3<n<15), it is found that the global minima obtained based on the basin-hopping method are identical to those reported by using the genetic algorithm [Iwamatsu, J. Chem. Phys. 112, 10976 (2000)], as well as with those by using molecular dynamics and the steepest-descent quench (SDQ) method [Feuston, Kalia, and Vashishta, Phys. Rev. B 37, 6297 (1988)]. However, for the mid-sized SW clusters (16<n<20), the global minima obtained differ from those based on the SDQ method, e.g., the appearance of the endohedral atom with fivefold coordination starting at n=17, as opposed to n=19. For larger SW clusters (20<n <30), it is found that the ‘‘bulklike’’ endohedral atom with tetrahedral coordination starts at 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)].

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