Dispersion corrections in the boron buckyball and nanotubes*

We have investigated structural and electronic properties of the B$_{80}$ buckyball and boron nan-otubes by means of dispersion-corrected density-functional calculations. Our analysis reveals the vibrational stability for the icosahedral B$_{80}$ with the inclusion of dispersion corrections, in contrast to the instability to a tetrahedral B$_{80}$ with puckered capping atoms from preceding density-functional theory calculations. Similarly, the dispersion-corrected density-functional calculations yield non-puckered boron nanotube conformations and an associated metallic state for zigzag tubes. Our study indicates that the incorporation of long-range dispersive interactions is particularly important to the structural and electronic properties of boron fullerenes and nanotubes.