Relaxation of icosahedral-cage silicon clusters via tight-binding molecular dynamics

Journal Article · Wed May 15 04:00:00 EDT 1991 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.43.11754· OSTI ID:5488089

Khan, F S ^[1]; Broughton, J Q ^[2]

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1. Department of Electrical Engineering, The Ohio State University, Columbus, Ohio 43210 (USA) Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (USA)
2. Complex Systems Theory Group, Naval Research Laboratory, Washington, D.C. 20375 (USA)

We have used a tight-binding total-energy expression for silicon to study the stability and structure of relatively large silicon clusters. Relaxation is performed using a fictitious Lagrangian and molecular dynamics. Specifically, we have looked at the relaxation of 50-, 60-, and 70-atom spheroidal hollow (icosahedral-cage-structure) clusters. We find that these clusters are not stable and relax into structures which look like puckered balls. Our results show that the unrelaxed clusters are metallic and the relaxed clusters are insulating with the Fermi level passing between localized states. We have also examined the relaxation of large clusters (size of about 100 atoms) extracted from pure diamond, fcc, and sc bulk silicon. We find that the cohesive energies of the relaxed icosahedral-cage clusters are greater than the relaxed diamond clusters and less than the relaxed fcc clusters. We also find that a single layer of flat silicon graphite is not stable and relaxes into a nonplanar layer with properties very similar to those of the relaxed icosahedral clusters.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5488089
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:14; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
CHARGE DENSITY
CRYSTAL STRUCTURE
ELEMENTS
RELAXATION
SEMIMETALS
SILICON
SIMULATION
SOLID CLUSTERS
STABILITY