Nanoalloy Simulation

The term "nanoalloy" is employed in recent scientific literature to design materials consisting of metal structures with at least one nanoscale dimension and composed by two or more different metals. Often, the term is restricted to nanoscale alloy particles, i.e., multicomponent metallic aggregates with diameters ranging between 1 and 100 nm.With respect to pure systems, nanoalloys present additional degrees of freedom of composition and chemical ordering, that is, the ratio among the elemental components can be varied as well as how these species are distributed within the nanostructure. By combining these variables with nanoscale confinement effects, it is possible to confer these nanomaterials' unique properties. They are therefore of great interest in basic science as well as in current nanotechnology and find applications in a variety of fields: from chemical sensing to heterogeneous catalysis and from magnetic recording to optoelectronic devices, thermal treatment of cancer, and "cell imaging," i.e., colorimetric probes for DNA detection [2]. Such interest at the experimental and industrial level has stimulated corresponding theoretical efforts, and a field of modern computational materials science is devoted to the prediction of the structure and properties of nanoalloys via simulations. While many theoretical methods here employed are borrowed from or shared with other fields, some are specific. For example, in nanoalloys the chemical ordering or compositional structure, i.e., the way in which the different chemical elements are positioned within a fixed structural framework, gives rise to a huge number of isomers called "homotops" [3]. The computational approaches used to deal with this issue by efficiently sampling the chemical ordering phase space are thus specific to the nanoalloy field.