title: Polymorphism of two-dimensional boron.
abstract: The structural stability and diversity of elemental boron layers are evaluated by treating them as pseudoalloy B(1-x)[hexagon](x), where [hexagon] is a vacancy in the close-packed triangular B lattice. This approach allows for an elegant use of the cluster expansion method in combination with first-principles density-functional theory calculations, leading to a thorough exploration of the configurational space. A finite range of compositions x is found where the ground-state energy is essentially independent of x, uncovering a variety of stable B-layer phases (all metallic) and suggesting polymorphism, in stark contrast to graphene or hexagonal BN.
authors.affiliation: Department of Mechanical Engineering and Materials Science and Department of Chemistry, Rice University, Houston, Texas 77005, USA.
authors.forename: Evgeni S
authors.initials: ES
authors.lastname: Penev
authors.forename: Somnath
authors.initials: S
authors.lastname: Bhowmick
authors.forename: Arta
authors.initials: A
authors.lastname: Sadrzadeh
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson