LiBeB: A predicted phase with structural and electronic peculiarities

Beginning an in-depth analysis of binaries and ternaries in the Li-Be-B system, we examine the static structures and electronic properties of LiBeB (i.e., 1:1:1) over a range of pressures. This as-yet unknown compound is predicted to possess a stable ground state at 1 atm and some higher pressures. As the pressure rises, LiBeB goes through a diverse series of structures, beginning with metallic structures, which feature chains and layers of atoms, progressing to structures built on “colorings” of the Laves phases, and containing helical arrangements of boron atoms, on to high-pressure phases that are ternary variants of a body-centered cubic (bcc) lattice. The density of states (DOS) at the Fermi level consistently falls in a pseudogap (sometimes a complete gap is predicted); LiBeB is unlikely to be a good metal or superconductor. The distribution of the DOS follows what electronegativity would predict—Li electrons are transferred to B. Some curious features of the LiBeB structures emerge, including near-icosahedral coordination, independent of atom type; in a range of pressures, a resemblance of the total DOS to that of metallic Be; and also a Dirac surface.