A combined stochastic search and density functional theory study on the neutral and charged silicon-based clusters MSi6 (M = La, Ce, Yb and Lu)

Abstract

The neutral and charged silicon clusters Si₆^q (q = 0, −1) are doped systematically with an external atom of different lanthanides: La, Ce, Yb and Lu. The structural, electronic, and magnetic properties of the doped clusters, MSi₆^q (M = La, Ce, Yb and Lu; q = 0, −1) are investigated using the Saunders “Kick” global stochastic search technique combined with density functional theory (DFT) calculations. The accuracy and consistency of structure optimization of MSi₆^q clusters are tested with three exchange correlation functionals (PBEPBE, BPW91 and B3LYP). DFT calculations show that the pentagonal bipyramid structures of MSi₆⁻ (M = Yb, Lu) and Si_6/7⁻ with high symmetry are ground state structures, which give simulated photoelectron spectra in good agreement with available experiments. The detailed comparison between previously published experimental photoelectron spectra, and the present theoretical simulation helps to identify the ground state structures. The neutral species shows the impurity as a four-coordinate atom in the equatorial plane of pentagonal bipyramid. Furthermore, the current magnetic property analysis indicates that the magnetic moments of the doped rare earth atoms remain largely localized, and the atomic-like magnetism is maintained in the doped clusters.