On the transition from Van der Waals- to metallic bonding in Hg-clusters as a function of cluster size
Abstract
The transition from insulating small Hgn clusters to metallic bulk-Hg is studied using a parametrized LCAO model. Our results for the size dependence of the cohesive energy show that covalent bonding is already important for n = 13-19, indicating that the transition from Van der Waals to covalent bonding should take place near this cluster size range. For n gtrsim 80 s- and p-bands overlap, the density of states resembles the bulk density of states and the gap at the Fermi-level is close to the limiting value Δn(n → ∞) = [N(ɛF)n]-1. Therefore, no important changes in the electronic structure occur for n > 80 and metallic-like optical properties similar to those observed for alkali-metal clusters are expected. For intermediate sizes (19 lesssim n lesssim 80) semiconducting like properties are expected. In qualitative agreement with experiment, we obtain for Hg-clusters an increase of the average bond-length of about 5% with respect to the bulk. The effects of electron correlations and surface relaxation are briefly discussed.
- Publication:
-
Physica Scripta
- Pub Date:
- October 1988
- DOI:
- 10.1088/0031-8949/38/4/022
- Bibcode:
- 1988PhyS...38..623P