Insights into the structure and growth of Lu-doped germanium clusters: comparing density functional theory calculations with photoelectron spectroscopy experiments

ABSTRACT

The structure and growth of a series of Lu-doped germanium clusters, LuGe_n^q (n = 2–14, q = 0, −1) have been investigated by previous photoelectron spectroscopy (PES) and density functional theory (DFT) calculations. The ground states of the anionic LuGe_n^– clusters obtained from DFT calculations are verified by comparing simulated PES with experimental results. The simulated PES for smaller clusters LuGe_n^– (n ≤ 6) display relatively simple spectral patterns, suggesting high symmetry structures. It is observed that the pentagonal bipyramid shape is the basic framework for the nascent growth process of LuGe_n^– (n = 2–8). The structures of LuGe_n^– (n = 2–13) clusters are all exohedral structures with the Lu atom adsorbed at the surface of the bare Ge_n^– clusters, while LuGe₁₄^– is the smallest endohedral Lu-doped germanium cluster with the Lu atom completely fallen into the germanium frame. It is found that the LuGe_n^– clusters with even n are more stable than those with odd n and in the LuGe_n clusters there is an opposite trend. Especially, the LuGe_n^q (n = 9, 12, q = 0, −1) clusters are extremely stable compared to other size clusters. HOMO–LUMO gap shows that the chemical stability of bare Ge_n^– (n = 2–14) clusters are stronger than that of LuGe_n^q (n = 2–14, q = 0, −1) clusters owing to the doping of a Lu atom.

GRAPHICAL ABSTRACT

KEYWORDS:

• Density functional theory
• geometry optimisation
• HOMO–LUMO gap
• structure evolution

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analysed during this study are included in this published article (and its supplementary information files).

Additional information

Funding

This work was supported by the Fujian Provincial Department of Science and Technology [grant number 2017J01001]; the National Natural Science Foundation of China [grant number 12074387]; the Science and Technology Plan of Quanzhou [grant numbers 2018C077R and 2018C078R], the New Century Excellent Talents in Fujian Province University [grant number 2014FJ-NCET-ZR07]; the Program for Excellent Youth in Fujian Province University [grant number JA13009].