Structural and energetic properties of nickel clusters: 2⩽N⩽150

Abstract

The four most stable structures of Ni N clusters with N from 2 to 150 have been determined using a combination of the embedded-atom method in the version of Daw, Baskes and Foiles, the variable metric/quasi-Newton method, and our own Aufbau/Abbau method. A systematic study of energetics, structure, growth, and stability of also larger clusters has been carried through without more or less severe assumptions on the initial geometries in the structure optimization, on the symmetry, or on bond lengths. It is shown that cluster growth is predominantly icosahedral with islands of fcc, tetrahedral and decahedral growth. For the first time in unbiased computations it is found that Ni 147 is the multilayer (third Mackay) icosahedron. Further, we point to an enhanced ability of fcc clusters to compete with the icosahedral and decahedral structures in the vicinity of N = 79. In addition, it is shown that conversion from the hcp/anti-Mackay kind of icosahedral growth to the fcc/Mackay one occurs within a transition layer including several cluster sizes. Moreover, we present and apply different analytical tools in studying structural and energetic properties of such a large class of clusters. These include means for identifying the overall shape, the occurrence of atomic shells, the similarity of the clusters with, e.g., fragments of the fcc crystal or of a large icosahedral cluster, and a way of analysing whether the N -atom cluster can be considered constructed from the (N − 1)-atom one by adding an extra atom. In addition, we compare in detail with results from chemical-probe experiment. Maybe the most central result is that first for clusters with N above 80 general trends can be identified.

Structural and Electronic Properties of Gold Clusters

“…Finally, we shall consider the overall shape of the clusters. As we showed in our earlier report on Ni clusters [40], it is convenient to study the 3 × 3 matrix containing the elements…”

“…Around N = 75 we see that a third atomic shell is being formed. We have earlier found [40] that it was useful to monitor the structural development of the isomer with the lowest total energy through the so-called similarity functions. We shall study how clusters grow and, in particular, if the cluster with N atoms can be derived from the one with N − 1 atoms simply by adding one extra atom.…”

“…In the EAM calculations we optimized the structure using our own Aufbau/Abbau method [38,39,40]. The method is based on simulating experimental conditions, where clusters grow by adding atom by atom to a core.…”

On the optical, electronic, and structural properties of zinc sulfide nanoclusters

“…This function is used to quantify structural differences and similarities in a set of clusters [53][54][55]. Using ZnS bond distances in various clusters, the quantity q is defined as follows [52]:…”

Analyzing the properties of clusters: Structural similarity and heat capacity

“…In earlier works [9,10] we have introduced descriptors, so called similarity functions, that were developed in order to quantify structural similarity. We shall here briefly outline their basic ideas, also because we will use these for comparison with the new measures and since we will discuss their limitations.…”