  Materials with Dirac point are so amazing since the charge carriers are
massless and have an effective speed of light. Among the reported
two-dimensional silicon allotropes, no one showing such exciting nature was
proved experimentally. This fact motivates us to search for other such
two-dimensional silicon allotropes. As a result, a new single atomic layer thin
silicon allotrope was predicted by employing CALYPSO code in this work. This
silicon allotrope is composed of eight- membered rings linked by Si-Si bonds
and presents buckling formation. Expectedly, the electronic calculation reveals
that there exists Dirac point at Fermi energy level. Furthermore, the ab initio
molecular dynamics simulations displays that the original atomic configuration
can be remained even at an extremely high temperature of 1000 K. We hope this
work can expand the family of single atomic layer thin silicon allotropes with
Dirac fermions.
