Global optimization of neutral and charged 20- and 55-atom silver and gold clusters at the DFTB level
Résumé
The global optimization of metallic clusters is an important topic because nanoclusters exhibit structure-dependent properties. In this paper, we present a global optimization study of , , and in their neutral and charge states (−1, 0, +1) conducted using a Parallel-Tempering Molecular Dynamics algorithm at the DFTB level without pre-screening. For , and their ions, the present DFTB low energy structures are in good agreement with previously published calculations and experimental data. In the case of and , the present study is consistent with photo-electron detachment experiments suggesting highly symmetric icosahedral structures for silver and more disordered morphologies for gold. The present results are also compatible with trapped ion electron diffraction experiments and calculations for and . We report low-energy isomers of exhibiting cavities below their external shell. This work quantitatively confirms the relevance of DFTB for structure calculation of noble metal clusters. Furthermore, it also demonstrates the feasibility of global optimization using DFTB, without pre-screening through classical potential, for sizes up to a few tens of atoms and for different charge states.
Domaines
Chimie théorique et/ou physique
Origine : Fichiers produits par l'(les) auteur(s)
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