Free standing double walled boron nanotubes Original Research Article

Based on density functional calculations we propose stable structures of free standing double walled boron nanotubes in the form of two single walled boron nanotubes (SWBNTs) inside one another. Puckering of the boron sheets allows the inner atoms of the outer wall and outer atoms of the inner wall to be matched giving spsp-type hybrid σσ bonding between the walls. The structural stability, in the case of double walled tubes, increases as the bond interaction between the walls strengthens. All the optimized structures reported in this study are electronically conducting in good agreement with the previously calculated metallic behavior of the experimentally observed SWBNTs.