Structure, stability, and electronic properties of niobium-germanium and tantalum-germanium clusters

Abstract

The structural, electronic and magnetic properties of niobium and tantalum doped germanium clusters MGen (M = Nb, Ta and n = 1-19) are investigated by first principles calculations within the Density Functional Theory approach (DFT). The growth pattern behaviors, stabilities, and electronic properties are presented and discussed. Endohedral cagelike structures in which the metal atom is encapsulated are favored for n ≥ 10. The doping metal atom contributes largely to strengthen the stability of the germanium cage-like structures with the binding energy ordered as follows BE(Gen+1) < BE (VGen) < BE(NbGen) < BE(TaGen). Our results highlight the relative high stability of NbGe15, TaGe15 and VGe14.

Electronic structures of NbGen−/0/+ (n = 1–3) clusters from multiconfigurational CASPT2 and density matrix renormalization group‐CASPT2 calculations

“…Also, the Nb Ge and Ge Ge bond orders vary from 1.84 and 0.82 in 3 A 2 to 1.42 and 1.07 in 4 B 1 . In the previous PBE functional calculations, although the spin state of the neutral cluster is not indicated, the Nb Ge and Ge Ge distances are reported to be 2.453 and 2.579 Å [7]. As compared to the CASPT2 results for the 4 B 1 neutral ground state in this work, the Nb Ge distance calculated with the PBE functional is almost the same, while the…”

“…[54] For analyzing the nature of the electronic Our CASPT2 results for the neutral cluster differ from the previous PBE density functional calculations. [7] In particular, the ground state of the neutral cluster is reported to be the sextet state by the PBE functional, [7] while it is predicted to be the 4 Φ by the CASPT2 although the energy difference between the quartet and sextet is just 0.05 eV. The same relative energy order of the quartet and sextet states is also found by the CASPT2 method in the case of VGe cluster.…”

“…The BP86, B3LYP, CASPT2, and DMRG-CASPT2 methods give different relative energy orders for the lowlying states of the neutral cluster as compared to the previous PBE functional calculations. [7] The PBE functional proposes a quartet as the ground state, [7] while our calculations favor the doublet states.…”

“…Transition metal-doped germanium clusters are widely investigated because of their potential applications as building blocks for nanomaterials. [1][2][3][4][5][6][7][8] Because properties of clusters depend on their geometric structure and atomic composition, a large number of transition metal-doped germanium clusters have been studied to search for stable clusters. Experimentally, the mass-selected anion photoelectron spectroscopy was applied to probe the geometric and electronic structures of many transition metal-doped germanium clusters.…”

“…[1, It was found in many cases that doping transition metal atom can lead to stable transition metal-doped germanium clusters. [1,2,6,7,19,21] Density functional theory is the most popular computational quantum chemical method to investigate the geometric and electronic structures of transition metal-doped germanium clusters. However, the accuracy of this method depends on the exchange-correlation functional.…”