Structural assignment, and electronic and magnetic properties of lanthanide metal doped silicon heptamers Si7M0/− with M = Pr, Gd and Ho

Abstract

The ground state geometries of neutral and anionic lanthanide-metal-doped silicon clusters Si₇M^0/− with M = Pr, Gd and Ho were determined by quantum chemical (DFT) computations and the previous experimental photoelectron spectra were assigned. The hybrid B3LYP functional is suitable for predicting the ground electronic states of these Si clusters and reproducing well their photoelectron spectra. All the most stable isomers are substitutive derivatives of the bicapped octahedral pure Si₈^0/− clusters. The bicapped octahedral Si₇M is generated by substituting one Si atom on a plane of the D_4h octahedron by one M atom. Replacement of a Si atom on the C₂ axis of another bicapped octahedron by a lanthanide metal atom, where two capping Si atoms are situated in front of opposite triangular face on the side of the central square, gives rise to the anionic Si₇M⁻. The limited participation of f-electrons of the lanthanide metal atoms on the valence electronic structure and thereby in the bonding of Si₇M^0/− induces high magnetic moments of the doped clusters. As a consequence, not only Si₇M^0/− but also Si_nLn^0/− clusters can be regarded as suitable building blocks for assembling silicon-based cluster magnetic materials.