Structures and Stabilities of Small Silicon Cluster: High-Level Ab initio Calculations of Si6

Abstract

The lowest-energy structure of Si6 has been controversial. In this paper, we studied relative stability of this cluster by using the B3LYP, PBE1PBE, MP2, MP4, CCSD, CCSD(T), and QCISD(T) calculations with large basis sets (cc-pVTZ and cc-pVQZ). Our results indicate that the octahedral structure (D4h) is the lowest-energy structure among three isomer candidates studied previously. Our results are also supported by a previous experimental measurement.