Electronic properties of double wall BN nanotube under hydrostatic pressure: an ab initio study Wesdney S. Melo, Mauro B. Pereira, Humberto F. Silva Filho and Silvete Guerini Eur. Phys. J. B, 88 1 (2015) 6 Published online: 02 January 2015 DOI: 10.1140/epjb/e2014-50410-0