Title: Si clusters are more metallic than bulk Si

Abstract

Dipole polarizabilities were computed using density functional theory for silicon clusters over a broad range of sizes up to N = 147 atoms. The calculated total effective polarizabilities, which include contributions from permanent dipole moments of the clusters, are in very good agreement with recently measured values. We show that the permanent dipole contributions are most important for clusters in the intermediate size range and that the measured polarizabilities can be used to distinguish between energetically nearly degenerate cluster isomers at these sizes. We decompose the computed total polarizabilities into the so-called dipole and charge transfer contributions, $α^p$ and $α^q$, using a sitespecific analysis. When the per-atom values of these quantities are plotted against $$N^{-1/3}$$, clear linear trends emerge that can be extrapolated to the large size limit ($$N^{-1/3}$$ → 0), resulting in a value for $$\frac{α}{N}$$ of 30.5 bohrs³/atom that is significantly larger than the per-atom polarizability of semiconducting bulk Si, 25.04 bohrs³/atom. This indicates that Si clusters possess a higher degree of metallicity than bulk Si, a conclusion that is consistent with the strong electrostatic screening of the cluster interiors made evident by the analysis of the calculated atomic polarizabilities.

Authors:

Jackson, Koblar  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5342-7978"

Jellinek, Julius ^[2]

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1. Central Michigan Univ., Mount Pleasant, MI (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division

Publication Date:

Wed Dec 28 00:00:00 EST 2016

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division

OSTI Identifier:

1418170

Alternate Identifier(s):

OSTI ID: 1364074

Grant/Contract Number:  

AC02-06CH11357; SC0001330

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Chemical Physics

Additional Journal Information:

Journal Volume: 145; Journal Issue: 24; Journal ID: ISSN 0021-9606

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Isomerism; Thermal fluctuations; Polarizability; Chemical bonding; HOMO-LUMO gap; Electrodynamics; Fullerenes; Density functional theory; Electrostatic screening; Dielectric properties