Threadlike Tin Clusters with High Thermal Stability Based on Fundamental Units

First-principles calculations using the density functional theory (DFT) have been carried out to study the geometric and electronic structures of Snn (n = 10–50) clusters. Our findings show that tin clusters (mainly based on Sn10 and Sn15 units) usually favor threadlike growth mode, rather than that of multibranch germanium or amorphous-like lead. Besides, a biatom-by-biatom oscillation with crossovers is shown, with the period between crossovers about ten atoms. Further studies on the electronic structures reveal that the charges of the highest occupied molecular orbital of Sn15 cluster accumulate at both ends, which can form strong covalent bonds with other units and give rise to a threadlike growth mode. Ab initio molecular dynamics simulations show that Snn (n = 10–50) clusters are usually stable even when the temperature is higher than the melting point of tin bulk. Our studies may provide some insight for an experiment to fabricate tin nanowires.