Structural, electronic and magnetic effects of Al-doped niobium clusters: a density functional theory study

Abstract

The application of the ab initio stochastic search procedure with Saunders "kick" method has been carried out for the elucidation of global minimum structures of a series of Al-doped clusters, Nb(n)Al (1 ≤ n ≤ 10). We have studied the structural characters, growth behaviors, electronic and magnetic properties of Nb(n)Al by the density functional theory calculations. Unlike the previous literature reported on Al-doped systems where ground state structures undergo a structural transition from the Al-capped frame to Al-encapsulated structure, we found that Al atom always occupies the surface of Nb(n)Al clusters and structural transition does not take place until n = 10. Note that the fragmentation proceeds preferably by the ejection of an aluminum atom other than niobium atom. According to the natural population analysis, charges always transfer from aluminum to niobium atoms. Furthermore, the magnetic moments of the Nb(n)Al clusters are mainly located on the 4d orbital of niobium atoms, and aluminum atom possesses very small magnetic moments.

Effects of All-Electron Basis Sets and the Scalar Relativistic Corrections in the Structure and Electronic Properties of Niobium Clusters

“…The ADZP and ADZP-DKH basis sets have shown good performance in the ab initio and DFT calculations when transition metal atoms are present ,,− in the molecule. Furthermore, the B3PW91 and M06 functionals were used in previous works with a good performance when applied in the electronic structure calculations of the metal clusters. − ,,, In order to better describe the clusters orbitals in the valence band, we have added one d function to the basis sets ADZP and ADZP-DKH for the Nb atom. All molecular calculations were performed with computational chemistry programs GAMESS and MOLPRO …”

“…Various theoretical studies of niobium clusters have been performed by many authors, − in the most cases, the density functional theory (DFT) together with the effective core potential (ECP), which is synonymous with pseudopotential (PP), is utilized. For the ECP approach, only the valence electrons are explicitly treated, and a few suitable functions are used to model the core.…”

Anion photoelectron spectroscopy and quantum chemical calculations of bimetallic niobium–aluminum clusters NbAln−/0 (n = 3–12): identification of a half-encapsulated symmetric structure for NbAl12−

“…47 The geometric structures, the growth behaviors and electronic properties of Nb n Al −/0 ( n = 4–12) were investigated using density functional theory calculations. 48,49…”