First principles study on the size evolution and stability of (AgF)n (n = 1–12) clusters

Abstract

The structural evolution of (AgF)n (n=1–12) clusters has been studied by first principles global minimization technique, namely, a genetic algorithm from density functional theory geometry optimization (GA-DFT). The growth sequence and pattern for n from 1 to 12 are analyzed from the perspective of geometric structures. The average binding energy per cluster, vertical and adiabatic ionization potentials, NICS-scan curves (partial clusters) are examined. The global minimum structures are planar single-ring conformations at n=1–5, and tubular conformations when n=6, 9 and 12, where they contain triangular units. When n=7 and 11, the clusters present butterfly and helix conformations, respectively. When n=8 and 10, the clusters are separate-ring structures. One more stable structure has been found for (AgF)6 cluster in comparison with previous work, indicating the power of DFT-based genetic algorithm in finding new structures for clusters. Several magic sizes of higher stability and symmetry are discovered. In particular, we find that when n=3, 6, 9 and 12, the clusters are tubular structures with high stability and high aromaticity.