First principles calculations of the electronic and geometric structure of Ag(27)Cu(7)nanoalloy

    Authors

    M. A. Ortigoza;T. S. Rahman

    Comments

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    Abbreviated Journal Title

    Phys. Rev. B

    Keywords

    CATALYTIC-ACTIVITY; CU-AU; AG-CU; CLUSTERS; METAL; GOLD; NOBLE; THERMODYNAMICS; NANOSTRUCTURES; NANOPARTICLES; Physics, Condensed Matter

    Abstract

    Ab initio calculations of the structure and electronic density of states (DOS) of the perfect core-shell Ag(27)Cu(7) nanoalloy attest to its D(5h) 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 Ag(27)Cu(7) and L1(2) 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 Ag(27)Cu(7), L1(2) 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 L1(2) Ag-Cu alloys, the Cu and Ag states hybridize significantly in Ag(27)Cu(7), 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 Ag(27)Cu(7) 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.

    Journal Title

    Physical Review B

    Volume

    77

    Issue/Number

    19

    Publication Date

    1-1-2008

    Document Type

    Article

    Language

    English

    First Page

    14

    WOS Identifier

    WOS:000256971600112

    ISSN

    1098-0121

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