Structural Evolution and Electronic Properties of Intermediate Sized Ti n (n=33--60) Clusters

Tailoring Titanium Carbide Clusters for New Materials: from Met-Cars to Carbon-Doped Superatoms

Tailoring materials with prescribed properties and regular structures is a critical and challenging research topic. Early transition metals were found to form supermagic M8C12 metallocarbohedrenes (Met-Cars); however, stable metal carbides are not limited to this common stoichiometry. Utilizing self-developed deep-ultraviolet laser ionization mass spectrometry, here, we report a strategy to generate new titanium carbides by reacting pure Tin clusters with acetylene. Interestingly, two products corresponding to Ti17C2 and Ti19C10 exhibit superior abundances in addition to the Ti8C12 Met-Cars. Using global-minimum search, the structures of Ti17C2 and Ti19C10 are determined to be an ellipsoidal D4d and a rod-shaped D5h geometry, respectively, both with carbon-capped Ti4C moieties and superatomic features. We illustrate the electronic structures and bonding nature in these carbon-doped superatoms concerning their enhanced stability and local aromaticity, shedding light on a new class of metal-carbide nanomaterials with atomic precision.

New Multicomponent Optimization Scheme for Equiatomic Vanadium-Titanium Nanoparticle Study

We present a new multicomponent structure prediction method named MRS-Swap searching, which is inspired by space symmetry and swap of different atomic species. For the pure titanium cluster, a new ground-state structure of the Ti20 cluster with higher symmetry relative to a previous study was found by our method. Based on the structural analysis of Tin (n = 2k, k = 2-11), Vn (n = 2k, k = 2-11), and TinVm (n = m = 2-11) systems, we found that the lowest energy structures of these three systems are very similar, which indicates that equiatomic vanadium-titanium-mixed clusters do not change their ground-state structure relative to the same size pure vanadium and titanium cluster. According to the structure-activity relationship, we conclude that the yield strength (σ) of macro vanadium-titanium alloy is between pure titanium and pure vanadium metal, and this can be expressed through σ(Ti) > σ(TiV) > σ(V). The X-ray diffraction results show that the V2Nb, TiVNb, and Ti2Nb alloys also have the same BCC structure, which may be related to their microstructure. Our method and results can be helpful for future multicomponent alloy design.

On the structure and electronic properties of Ptn clusters: new most stable structures for n = 16-17

The lowest energy structures and electronic properties of Ptn clusters up to n = 17 are investigated by using a genetic algorithm in combination with density functional theory calculations. There are several putative global minimum structures for platinum clusters which have been reported by using different approaches, but a comprehensive study for n = 15-17 has not been carried out so far. Herein, we perform a consensus using GGA (PBE), meta-GGA (TPSS) and hybrid (B3PW91, PBE0, PBEh-3c, M06-L) functionals in conjunction with the Def2-TZVP basis set. New most stable structures are found for Pt16 and Pt17, which are slightly lower in energy than the previously reported global minima. Molecular dynamics simulations show that the clusters are rigid at room temperature. We analyze the structural, electronic, energy and vibrational data of the investigated clusters in detail.