Energetics of charged metal clusters containing vacancies


الملخص بالإنكليزية

We study theoretically large metal clusters containing vacancies. We propose an approach, which combines the Kohn-Sham results for monovacancy in a bulk of metal and analytical expansions in small parameters $c_{v}$ (relative concentration of vacancies) and $R_{N,v}^{-1}$, $R_{N,v}$ being cluster radius. We obtain expressions of the ionization potential and electron affinity in the form of corrections to electron work function, which require only the characteristics of 3D defect-free metal. The Kohn-Sham method is used to calculate the electron profiles, ionization potential, electron affinity, electrical capacitance, dissociation, cohesion and monovacancy-formation energies of the small perfect clusters Na$_{N}$, Mg$_{N}$, Al$_{N}$ ($N leq 270$) and the clusters containing a monovacancy ($Ngeq 12$) in the stabilized-jellium model. The quantum-sized dependences for monovacancy-formation energies are calculated for the Schottky scenario and the bubble blowing scenario, and their asymptotic behavior is also determined. It is shown that the asymptotical behaviors of size dependences for these two mechanisms differ from each other and weakly depend on the number of atoms in the cluster. The contribution of monovacancy to energetics of charged clusters, the size dependences of their characteristics and asymptotics is discussed. It is shown that difference between the characteristics for the neutral and charged cluster is entirely determined by size dependences of ionization potential and electron affinity. Obtained analytical dependences may be useful for the analysis of the results of photoionization experiments and for the estimation of the size dependences of the vacancy concentration including the vicinity of the melting point.

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