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 ⁺ (n = 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 (n = 9) and always preserves it in the a priori chiral one (n = 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 AgCu ₁₀ ⁺(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.