Eur. Phys. J. Plus (2020) 135: 734
https://doi.org/10.1140/epjp/s13360-020-00745-6

Regular Article

Structures, stabilities and electronic properties of Ti_mSi_n⁻ (m = 1‒2, n = 14‒20) clusters: a combined ab initio and experimental study

¹ Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, 116024, Dalian, China
² School of Ocean Science and Technology, Dalian University of Technology, Panjin Campus, 124221, Panjin, China
³ Tianjin International Center of Nanoparticles and Nanosystem, Tianjin University, 300072, Tianjin, China
⁴ Department of Physics and FMF, University of Freiburg, 79104, Freiburg, Germany

ⁿ zhaojj@dlut.edu.cn

Received: 9 July 2020
Accepted: 2 September 2020
Published online: 16 September 2020

Abstract

Titanium-doped silicon clusters anions, Ti_mSi_n⁻ (m = 1‒2, n = 14‒20), have been investigated by photoelectron spectroscopy and density functional theory (DFT) calculations. Low-energy structures of Ti_mSi_n⁻ clusters have been globally searched using a genetic algorithm combined with DFT calculations. The electronic density of states and vertical detachment energies have been computed at the HSE06/aug-cc-pVDZ level and compared to the experimental data. Excellent agreement is found between theory and experiment especially in case of the singly doped clusters. In general, clusters with size m + n ≤ 17 prefer cage structures, while larger sized clusters evolve on a quasi-fullerene Ti@Si₁₄ structural motif. Natural population analysis reveals that the Ti atoms possess negative charges and thus act as electron acceptors. The calculated binding energies and HOMO–LUMO gaps show that the clusters with cage structures have significantly higher stability, particularly Ti₁Si₁₆⁻ and Ti₂Si₁₅⁻. One reason is that neutral Ti₂Si₁₅ exhibits a closed-shell electronic structure as a superatom, like Ti₁Si₁₆.