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Results of a theoretical study of the properties of Sin, Gen, and SinGen clusters are presented. An approximate density-functional method in combination with genetic algorithms have been used in an unbiased determination of the structures of the lowest total energy. The resulting structural, energetic, and electronic properties are analysed and compared with each other for the different systems. [ABSTRACT FROM AUTHOR]

Results of a theoretical study of the lowest-energy structures of (KCs)n and (RbCs)n bimetallic clusters with N=2n up to 50 atoms are presented. We observed the presence of a dominant structural motif, the fivefold pancake, in the structural evolution of the binary (KCs)n and (RbCs)n clusters with size. Moreover, the bimetallic clusters display a much more regular growth behaviour compared to that of the monoatomic KN, RbN and CsN clusters. The obtained geometries belong to a family of pIh structures reported recently for series of binary transition metal clusters. [ABSTRACT FROM AUTHOR]

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]

Using a parameterized density-functional tight-binding method we have calculated the electronic and structural properties of Ge–Si nanoparticles. Starting with a spherical part of a zinc-blende/diamond crystal (with the center of the sphere at the mid-point of a nearest-neighbour bond) we have constructed initial structures that subsequently were allowed to relax. Structures consisting solely of Ge atoms or solely of Si atoms were studied, together with core-shell structures for which one semiconductor forms a shell on the core of the other semiconductor. Moreover, homogeneous, ordered SiGe structures as well as structures with a semisphere of one semiconductor and a semisphere of the other were also considered. In analysing the results special emphasis is put on identifying particularly stable structures, on explaining the occurrence of those, on the spatial distribution of the frontier orbitals, and on the variation of the total energy with structure and composition. [ABSTRACT FROM AUTHOR]

The geometries and electronic properties of the most stable small Aun clusters with n=2 to 20 are presented. An intensive search for low-energy minima of Aun clusters was carried through using a density-functional tight-binding method combined with genetic algorithms for an unbiased global structure optimization. The structural and energetic properties of the small gold clusters are compared with those of planar Aun clusters with n=5 to 15. [ABSTRACT FROM AUTHOR]

The geometries and electronic properties of the most stable small Aun clusters with n=2 to 20 are presented. An intensive search for low-energy minima of Aun clusters was carried through using a density-functional tight-binding method combined with genetic algorithms for an unbiased global structure optimization. The structural and energetic properties of the small gold clusters are compared with those of planar Aun clusters with n=5 to 15. [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]