An Ab Initio Study on the Structural, Electronic and Optical Properties
of Inverted Sandwich Monocyclic Small Boron Clusters
ZnnBm (n=1, 2; m=6-8)
Abstract
For the past decades, experiment like photoelectron spectroscopy and
computational studies have demonstrated that highly coordinated
transition metal centered boron nanoclusters favor planar or
quasi-planar type structures, which could be potential building blocks
for designing better nanostructure with tailored properties. In this
paper, we have studied geometrical structures, electronic, optical and
magnetic properties of the gas-phase Zn centered small boron clusters (n
= 6–8) by employing density functional theory (DFT) and time dependent
(TD) DFT calculations with B3LYP hybrid exchange-correlation functional.
Two global minimum structures containing pyramidal and bi-pyramidal
shaped ZnBm and Zn2Bm
clusters shows symmetrical cyclic motif. The adsorption energy,
ionization potential and molecular orbital analysis revealed that Zn is
chemically adsorbed on the boron clusters occupying the hollow site and
inverse sandwich bi-pyramidal (Zn2Bm)
clusters are relatively more stable compared to singly doped boron
nanoclusters. Vibrational modes are calculated to validate the true
minima nature of the optimize structures which possesses no imaginary
frequencies. All the pyramidal and bi-pyramidal clusters are optically
active and show blue shifts in our calculated absorption spectra. The
DFT computations indicate spin polarization in the pristine B7 cluster
which induces strong ferromagnetism in pristine and adsorbed B7
clusters.