An optimization scheme for atomic cluster structures, based on exaggerating the importance of the gravitational force, is introduced. Results are presented for calculations on Lennard-Jones clusters of 13, 38, and 55 atoms, and the 13-atom Morse cluster.

Cluster secondary ion mass spectrometry (cluster SIMS) has played a critical role in the characterization of polymeric materials over the last decade, allowing for the ability to obtain spatially resolved surface and in-depth molecular information from many polymer systems. With the advent of new molecular sources such as C(60)(+), Au(3)(+), SF(5)(+), and Bi(3)(+), there are considerable increa...

Using a combined quantum mechanical/classical method, we study the dynamics of deposition of small Na clusters on Ar(001) surface. We work out basic mechanisms by systematic variation of substrate activity, impact energy, cluster orientations, cluster sizes, and charges. The soft Ar material is found to serve as an extremely efficient shock absorber which provides cluster capture in a broad ran...

A new size-selected cluster deposition technique referred to as "parallel-deposition" is presented. An ion beam of multi-sized Aun clusters was spatially separated into individual cluster sizes by utilizing a Wien filter and the clusters spatially separated based on their atomic sizes were simultaneously deposited on a SiO2/Si(100) substrate. Parallel-deposited Aun clusters (n = 6, 7, and 8) on...

How does magnetism behave when the physical dimension is reduced to the size of nanostructures? The multiplicity of magnetic states in these systems can be very rich, in that their properties depend on the atomic species, the cluster size, shape and symmetry or choice of the substrate. Small variations of the cluster parameters may change the properties dramatically. Research in this field has ...

Deterministic optimization algorithms, that are combination of direct search methods and local search algorithms, are proposed for molecular conformation problems. We apply these methods to solve the Lennard-Jones atomic cluster problem. The deterministic optimization algorithms are embedded in a build-up scheme. At each stage, an atom is added to an optimized structure of a small cluster, and ...

Metallic glasses are metallic alloys that exhibit exotic material properties. They may have fractal structures at the atomic level, but a physical mechanism for their organization without ordering has not been identified. We demonstrated a crossover between fractal short-range (<2 atomic diameters) and homogeneous long-range structures using in situ x-ray diffraction, tomography, and molecular ...