Title: Two-dimensional boron on Pb (110) surface,
Abstract: We simulate boron on Pb(110) surface by using ab initio evolutionary
methodology. Interestingly, the two-dimensional (2D) Dirac Pmmn boron can be
formed because of good lattice matching. Unexpectedly, by increasing the
thickness of 2D boron, a three-bonded graphene-like structure (P2_1/c boron)
was revealed to possess double anisotropic Dirac cones. It is 20 meV/atom lower
in energy than the Pmmn structure, indicating the most stable 2D boron with
particular Dirac cones. The puckered structure of P2_1/c boron results in the
peculiar Dirac cones, as well as substantial mechanical anisotropy. The
calculated Young's modulus is 320 GPa.nm along zigzag direction, which is
comparable with graphene.