Title

First Principles Calculations Of The Electronic And Geometric Structure Of Ag27 Cu7 Nanoalloy

Abstract

Ab initio calculations of the structure and electronic density of states (DOS) of the perfect core-shell Ag27 Cu7 nanoalloy attest to its D5h symmetry and confirm that it has only six nonequivalent (two Cu and four Ag) atoms. The analyses of bond length, average formation energy, and heat of formation of Ag27 Cu7 and L 12 bulk Ag-Cu alloys provide an explanation for the relative stability of the former with respect to the other nanoalloys in the same family. The highest occupied molecular orbital-lowest unoccupied molecular orbital gap is found to be 0.77 eV, which is in agreement with previous results. The analyses of the DOS of Ag27 Cu7, L 12 Ag-Cu alloys, and related systems provide insight into the effects of low coordination, contraction or expansion, and the presence of foreign atoms on the DOS of Cu and Ag. While some characteristics of the DOS are reminiscent of those of the phonon-stable L 12 Ag-Cu alloys, the Cu and Ag states hybridize significantly in Ag27 Cu7, compensating for the d -band narrowing that each atom undergoes and hindering the dip in the DOS found in the bulk alloys. Charge density plots of Ag27 Cu7 provide further insight into the relative strengths of the various interatomic bonds. Our results for the electronic and geometric structures of this nanoalloy can be explained in terms of length and strength hierarchies of the bonds, which may have implications also for the stability of alloys in any phase or size. © 2008 The American Physical Society.

Publication Date

5-5-2008

Publication Title

Physical Review B - Condensed Matter and Materials Physics

Volume

77

Issue

19

Number of Pages

-

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1103/PhysRevB.77.195404

Socpus ID

43449096923 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/43449096923

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