The structural properties of free nanoclusters are reviewed. Special attention is paid to the interplay of energetic, thermodynamic, and kinetic factors in the explanation of cluster structures that are actually observed in experiments. The review starts with a brief summary of the experimental methods for the production of free nanoclusters and then considers theoretical and simulation issues, always discussed in close connection with the experimental results. The energetic properties are treated first, along with methods for modeling elementary constituent interactions and for global optimization on the cluster potential-energy surface. After that, a section on cluster thermodynamics follows. The discussion includes the analysis of solid-solid structural transitions and of melting, with its size dependence. The last section is devoted to the growth kinetics of free nanoclusters and treats the growth of isolated clusters and their coalescence. Several specific systems are analyzed.

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Structural properties of nanoclusters: Energetic, thermodynamic, and kinetic effects

The key methods for the preparation of magnetic nanoparticles are described systematically. The experimental data on their properties are analysed and generalised. The main theoretical views on the magnetism of nanoparticles are considered.

https://iopscience.iop.org/article/10.1070/RC2005v074n06ABEH000897/pdf

Magnetic nanoparticles: preparation, structure and properties

A review is presented of the design and application of genetic algorithms for the geometry optimisation of clusters and nanoparticles, where the interactions between atoms, ions or molecules are described by a variety of potential energy functions. A general introduction to genetic algorithms is followed by a detailed description of the genetic algorithm program that we have developed to identify the lowest energy isomers for a variety of atomic and molecular clusters. Examples are presented of its application to model Morse clusters, ionic MgO clusters and bimetallic “nanoalloy” clusters. Finally, a number of recent innovations and possible future developments are discussed.

Evolving better nanoparticles: Genetic algorithms for optimising cluster geometries

The physical and chemical properties of cluster systems at the subnano and nanoscale are often found to differ from those of the bulk and display a unique dependence on size, geometry, and composition. Indeed, most interesting are systems which have properties that vary discontinuously with the number of atoms and composition, rather than scale linearly with size. This realm of cluster science where “one atom makes a difference” is undergoing an explosive growth in activity, and as a result of extensive collaborative activities through theory at VCU and experiment at PSU, our groups are recognized as pioneers in this area in which we have been active for many years. Herein we provide an overview of the field with primary focus on our joint undertakings which have spawned the superatom concept, giving rise to a 3-D periodic table of cluster elements and the prospect of using these as building blocks of new nanoscale materials with tailored properties.

Clusters, Superatoms, and Building Blocks of New Materials†

Electronic and atomic structure, and magnetism of transition-metal clusters.

Electronic structure of 13-atom clusters of 4d nonmagnetic solids Pd, Rh, and Ru has been studied using a linear combination of atomic orbitals molecular-orbital approach within the density functional formalism. ${\mathrm{Pd}}_{13}$, ${\mathrm{Rh}}_{13}$, and ${\mathrm{Ru}}_{13}$ are all found to have nonzero magnetic moments. Unexpectedly, the ground state of ${\mathrm{Rh}}_{13}$ is found to have 21 unpaired electrons and thus a magnetic moment of 21${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$. These 4d-element magnetic moments are a result of the reduced dimensionality and the enhanced electronic degeneracy due to the symmetry of the cluster. The effect of impurities on the moments is examined through calculations on ${\mathrm{FePd}}_{12}$, ${\mathrm{FeRh}}_{12}$, ${\mathrm{RhPd}}_{12}$, and ${\mathrm{RuPd}}_{12}$ clusters.

Giant magnetic moments in 4d clusters.

The structure and spin configuration of a Gd{sub 13} cluster has been examined using theoretical electronic structure calculations and a Heisenberg model. The structure calculations show that the ground state geometry of the cluster has an hcp arrangement with a slightly reduced nearest-neighbor distance compared to bulk and an average moment of 7.8 {mu}{sub {ital B}}/atom. The Heisenberg model is calculated using an RKKY-like interaction. The effects of competing ferromagnetic and antiferromagnetic coupling for the nearest- and next-nearest-neighbor interaction, respectively, is investigated. It is shown that for a range of interaction strengths the spins assume a canted configuration. This effect leads to lower net magnetization of the cluster, and accounts for the anomalous low moments of Gd{sub {ital n}} clusters which have been experimentally observed. {copyright} {ital 1996 The American Physical Society.}

Spin configuration of Gd13 clusters.

The magnetic behavior of small clusters with antiferromagnetic interactions has been studied The clusters are modeled as Ising spins located at the atomic sites, interacting via a nearest-neighbor antiferromagnetic coupling The magnetic moments of these Ising clusters at various temperatures and magnetic fields have been calculated using Monte Carlo simulations We have studied clusters having icosahedral and cuboctahedral arrangements and containing between 13 and 561 atoms Our results show that the variation of magnetization with applied field and the temperature depends on the geometry of the clusters For icosahedral clusters, the calculated behavior indicates that the clusters have free spins and behave as frustrated paramagnets On the other hand, cuboctahedral clusters show well-defined ground states indicating that the finite size quenches the frustration inherent in the fcc lattice We also show that the magnetization for a given cluster size depends on the cluster geometry The theoretical predictions will be compared with recent measurements of the magnetic moment of the ${\mathrm{Cr}}_{\mathit{n}}$ clusters

Effect of geometry on magnetism in small antiferromagnetic clusters.

As technology develops, robots are increasingly becoming a part of our daily life. Applications include those for rehabilitation, assisted living, education, domestic help, and warfare. All these applications require specific control strategies and controllers. To combat this, recently developed depth sensors resolve the issue relating to input response and latency issues with immediate response time. Our project presents a robotic system that can imitate human motions and work accordingly. while compared to other motion sensors, the Raspberry Pi camera makes the device more comfortable to use while collecting human movements. The gadget extracts the robot's skeletal data, which is then processed to create the robot's joint angles. The proposed design of the robot imitates the human in real-time with very little or no lag. The Raspberry Pi camera that we employ can monitor joint locations in order to create software application gesture detection and mapping into control instructions that the robotic system can display.

Design and Implementation of Motion Imitation Robot

This work intends to demonstrate a simple method for creating models suitable for 3D printing or other digital manufacturing equipment using a Kinect-based scanner. The output of Kinect-based scanners is a depth map, and they often need complex computer operations to prepare them for digital production. For professional and recreational use alike, new depth cameras that have hit the market in recent years have opened up a wealth of exciting new possibilities for creatives. The Microsoft Kinect sensor, which was initially included with the Xbox 360 video game system, serves as an example of such a camera. In this article, a system is given that makes use of this device to build a 3D reconstruction of an interior environment that is as realistic as feasible. This article explains the use of an RGB-D camera to create a 3D model of an interior scene (Microsoft Kinect V2.0). Since the release of the Microsoft Kinect sensor, 3D mapping and localization have been an increasingly popular study area.

B. V. Reddy

Papers

Giant magnetic moments in 4d clusters.

Spin configuration of Gd13 clusters.

Effect of geometry on magnetism in small antiferromagnetic clusters.

Design and Implementation of Motion Imitation Robot

Creating Models for 3D printing Using Kinect based Scanners