Lægsgaard, J.Stokbro, K.2004-12-272004-12-2720012001http://hdl.handle.net/2003/1927610.17877/DE290R-1986enThe American Physical SocietyPhysical Review Letters530Hole Trapping at Al impurities in Silica: A Challenge for Density Functional Theories10.1103/PhysRevLett.86.2834article (journal)