  The effects of partial hydrogenation on the structure and electronic
properties of boron nitride nanotubes are investigated via density functional
theory calculations. We find that the structure of the nanotube may
considerably deform depending on the exact locations of the hydrogen atoms
adsorption. Furthermore, depending on the tube identity, diameter, and
adsorbate density it is found that the bandgap can be gradually reduced as a
function of the relative position of the hydrogen atoms and in some cases
change its character from indirect to direct and vice versa upon hydrogen
adsorption. Our findings indicate that partial hydrogenation may prove as a
valuable and experimentally achievable route for controlling the electronic
properties of boron nitride nanotubes.
