Abstract
We investigate the structural, electronic, and vibrational properties of
graphene nanoflakes (GNFs) with a small number of atoms (<250) and
distinct shapes (triangular, rectangular, and hexagonal) through
classical molecular dynamics (CMD) and density functional theory (DFT)
calculations. We show that these graphene nanostructures are able to
retain their planarity for simulated temperatures up to 1500 I. starting
to degrade into amorphous nanocarbon for temperatures above 3000 K. The
shapes and types of border of the GNFs have a strong influence on their
electronic properties and spin. The HOMO-LUMO energy nap of the studied
nanoflakes spans the full range of the visible spectrum, suggesting
potential applications M the fabrication of optical emission
nanodevices, which is confirmed by TDDFT. calculations to obtain the
UV-vis absorption spectra of triangular armchair GNFs. In particular,
the UV-vis maximum absorption energies and intensities scale linearly
with the linear size of the GNF. In the special case of zigzag-edged
triangular nanoflakes. a nonzero net spin which increases linearly with
the edge size was found, pointing toward possible spintronic
applications by tuning the spin distribution. The DFT calculations of
the infrared spectra allowed the identification of shape- and
border-related fingerprints.
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