Study of structures and thermodynamics of CuNi nanoalloys using a new DFT-fitted atomistic potential

Shape, stability and chemical ordering patterns of CuNi nanoalloys are studied as a function of size, composition and temperature. A new parametrization of an atomistic potential for CuNi is developed on the basis of ab initio calculations. The potential is validated against experimental bulk properties, and ab initio results for nanoalloys of sizes up to 147 atoms and for surface alloys. The potential is used to determine the chemical ordering patterns of nanoparticles with diameters of up to 3 nm and different structural motifs (decahedra, truncated octahedra and icosahedra), both in the ground state and in a wide range of temperatures. The results show that the two elements do not intermix in the ground state, but there is a disordering towards solid-solution patterns in the core starting from room temperature. This order-disorder transition presents different characteristics in the icosahedral, decahedral and fcc nanoalloys

Chirality in Copper Nanoalloy Clusters

It is shown that chirality is common in bimetallic clusters. Specifically, a detailed computational study of two copper clusters, Cu_n⁺ (<i>n</i> = 9,11), demonstrates that exchange of one copper atom with another metal atom (Ni, Zn, Ag, or Au) at various locations, leads, in most cases, to chirality in the a priori achiral cluster (<i>n</i> = 9) and always preserves it in the a priori chiral one (<i>n</i> = 11). Chirality was evaluated on a quantitative level, employing the Continuous Chirality Measure methodology, in two versions: a purely geometric structure analysis, and an analysis which takes into account the different nature of the atoms. Physical aspects of chirality were demonstrated by emergence of vibrational circular dichroism signals and by the emergence of parity violation (PV) energy difference, which is calculated by employing a quasi-relativistic approach. In the case of AgCu₁₀⁺(p9), the PV energy splitting value is about ∼10^–15 Hartree, bringing this nanoalloy close to the range of systems that have been discussed as promising candidates for a measurement of this phenomenon on the molecular level

Solid-state structural transformations from 2D interdigitated layers to 3D interpenetrated structures

10.1002/anie.201104106Angewandte Chemie - International Edition504610949-10952ACIE