Effects of a transverse electric field on the electronic properties of single- and multi-wall BN nanotubes

► Significant reduction on the formation and gap energies are observed for D>10 Å. ► The modifications in the formation and gap energies arise from the Stark effect. ► For multi-walled tubes, a more selective mechanism takes place. ► Only the (5,0)@(13,0) double walled tube shows significant gap narrowing.