Qualitative feature of the low-lying spectrum of intrashell states of   4-valence-electron atoms derived from symmetry consideration
  Inherent nodal surfaces existing in the wavefunctions of intrashell states of 4-valence-electron atoms have been investigated. The decisive effect of these surfaces has been demonstrated, the ordering of low-lying levels has been predicted, a primary classification scheme has been proposed, the existence of three rotation bands has been suggested. 
C.G.Bao (Dept. of Phys., Zhongshan Univ.,Guangzhou, P.R.China)