Origin of quasi-constant pre-exponential factors for adatom diffusion on Cu and Ag surfaces

    Authors

    H. Yildirim; A. Kara;T. S. Rahman

    Comments

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    Abbreviated Journal Title

    Phys. Rev. B

    Keywords

    TOTAL-ENERGY CALCULATIONS; EMBEDDED-ATOM-METHOD; WAVE BASIS-SET; MOLECULAR-DYNAMICS; LATTICE-VIBRATIONS; SELF-DIFFUSION; ELECTRON-GAS; METALS; PD; NI; Physics, Condensed Matter

    Abstract

    Many-body interaction potentials from the embedded atom method with two functionals and electronic structure calculations based on density functional theory and the plane-wave pseudopotential method are used to calculate the pre-exponential factors for self-diffusion of adatoms via hopping on Cu(100) and Ag(100) surfaces with and without steps. The pre-exponential factors are found to be in the range of 10(-3) cm(2)/s for all investigated processes regardless of whether substrate vibrational dynamics are included or omitted. When substrate dynamics are ignored, compensation effects between stiffening and softening of the vibrational frequencies of the diffusing atom are responsible for this quasi-constant pre-exponential. When these dynamics are included, subtle cancellations in the vibrational free energy make the local contribution of the diffusing atom the dominant one.

    Journal Title

    Physical Review B

    Volume

    76

    Issue/Number

    16

    Publication Date

    1-1-2007

    Document Type

    Article

    Language

    English

    First Page

    10

    WOS Identifier

    WOS:000250620600107

    ISSN

    1098-0121

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