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An analytic modified embedded atom method (MEAM), developed for bulk alkali metals, is used to identify up to six different, energetically lowest isomers of Li N and Na N clusters (N = 2 − 150) within an unbiased global structure-optimization procedure. Randomly generated clusters are locally optimized using the quasi-Newton method and the resulting six most stable isomers are used afterwards in the Aufbau–Abbau algorithm. Due to its analytical formulae and its semiempirical nature, the MEAM emerges as a fast and efficient method that is particularly suitable for an unbiased global optimization. Structural and energetic analyses show that the MEAM provides compact clusters that are in good agreement with the results of other semiempirical calculations. Occasionally, the MEAM produces structures that are normally not found with such model potentials but in more accurate DFT or ab initio studies. Moreover, clusters of pronounced stability (magic sizes) are identified, growth patterns are studied, and trends can be recognized in which the atomic arrangement within the clusters of the considered size range corresponds more to the fcc than to the bcc packing. Additionally, for most cluster sizes the structures of the lowest-energy isomers of Li N and Na N clusters are very similar. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lowest-energy structures (LES) of silver and copper clusters with N from 2 up to 150 atoms. [•] Calculation of the optical absorption spectra of the LES of Ag and Cu clusters using the classical Mie–Gans theory. [•] The spectra of the Ag clusters possess clearly identifiable shape-dependent plasmon peaks. [•] The absorption spectra for the Cu clusters are size/shape independent and do not show any plasmon peak. [•] Artificial Cu clusters: extremely oblate or prolate, show intensive and strongly shape-dependent maxima in good agreement with TDDFT calculations. [•] Good agreement with experiment and more complex TDDFT computations for silver clusters. [Copyright &y& Elsevier]

The soft deposition of Ni13 and Cu13 clusters on Ni(111) and Cu(111) surfaces is studied by means of constant-energy molecular-dynamics simulations. The atomic interactions are described by the Embedded Atom Method. It is shown that the shape of the nickel clusters deposited on Cu(111) surfaces remains rather intact, while the copper clusters impacting on Ni(111) surfaces collapse forming double and triple layered products. Furthermore, it is found that for an impact energy of 0.5 eV/atom the structures of all investigated clusters show the lowest similarity to the original structures, except for the case of nickel clusters deposited on a Cu(111) surface. Finally, it is demonstrated that when cluster and substrate are of different materials, it is possible to control whether the deposition results in largely intact clusters on the substrate or in a spreading of the clusters. This separation into hard and soft clusters can be related to the relative cohesive energy of the crystalline materials. [ABSTRACT FROM AUTHOR]

In this work we present results from a theoretical study on the properties of sodium clusters. The structures of the global total-energy minima have been determined using two different methods. With the parameterized density-functional tight-binding method (DFTB) combined with a genetic-algorithm we investigated the properties of NaN clusters with cluster size up to 20 atoms, and with our own Aufbau/Abbau algorithm together with the embedded-atom method (EAM) up to 60 atoms. The two sets of results from the independent calculations are compared and a stability function is studied as function of the cluster size. Due to the electronic effects included in the DFTB method and the packing effects included in the EAM we have obtained different global-minima structures and different stability functions. [ABSTRACT FROM AUTHOR]

The most stable structures of CuN, NiN, and AuN clusters with 2≤N≤60 have been determined using a combination of the embedded-atom (EAM), the quasi-Newton, and our own Aufbau/Abbau methods for the calculation of the total energy for a given structure, the structures of the local total-energy minima, and the structure of the global total-energy minimum, respectively. We have employed two well-known versions of the EAM: (1) the ‘bulk’ version of Daw, Baskes, and Foiles and (2) the Voter-Chen version which takes into account also properties of the dimer in the parameterization. The lower-energy structures (also for the smallest) of CuN and NiN clusters (i.e., structural details as well as symmetry) obtained with the two versions are very similar. Thus, our study supports an universality of the bulk embedding functions for copper and nickel. But for gold clusters the differences between structures calculated with the two different versions of the EAM are significant, even for larger clusters. [ABSTRACT FROM AUTHOR]