Density-functional calculations for prototype metal-boron nanotubes

Nanotubular materials inspired by crystalline diborides such as ${\mathrm{AlB}}_2$ are proposed. The atomic structure, in particular the basic chemical question of where to put Al atoms in order to stabilize nanotubular Al-B systems, is investigated using density-functional calculations for prototype systems. The optimized tubular prototypes are found to be competitive in energy with their bulk crystalline counterparts. All of the tubular Al-B systems investigated are calculated to be metallic.