Dear Munima, I have in fact come across a study that claims that Ba 4d states would make a difference : JAP 100, 086103 (2006) Best wishes, Hande -- Hande Toffoli Department of Physics Office 439 Middle East Technical University Ankara 06531, Turkey Tel : +90 312 210 3264 http://www.physics.metu.edu.tr/~hande