A two-dimensional carbon allotrope, Stone-Wales graphene, is identified in
stochastic group and graph constrained searches and systematically investigated
by first-principles calculations. Stone-Wales graphene consists of
well-arranged Stone-Wales defects, and it can be constructed through a
90∘ bond-rotation in a 8×8 super-cell of
graphene. Its calculated energy relative to graphene, +149 meV/atom, makes it
more stable than the most competitive previously suggested graphene allotropes.
We find that Stone-Wales graphene based on a 8 super-cell is more
stable than those based on 9×9, 12×12 and 13×13 super-cells, and is a "magic size"
that can be further understood through a simple "energy splitting and
inversion" model. The calculated vibrational properties and molecular dynamics
of SW-graphene confirm that it is dynamically stable. The electronic structure
shows SW-graphene is a semimetal with distorted, strongly anisotropic Dirac
cones.Comment: Accepted;5 pages;5 figures;53 references and 8 pages of supplementary
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