Structure of molecular energy levels of homonuclear diatomic molecules

A new approach is given for the systematic prediction of the low-lying elec tronic states of homonuclear diatomic molecules. The approach is based on t he bond order and the energy levels of the separated atoms. The asymptotic wave functions are derived from two atomic wave functions by using new oper ators defined as linear combinations of certain ladder operators. We show t hat the low angular moment states tend to have a high bond order in the sta tes derived from an asymptote. The observed low-lying states of C-2, C-2(+) , Sc-2, and Ti-2 molecules agree with the predictions. (C) 1999 John Wiley & Sons, Inc.