Hagedorn G.A. , Joye A.
Landau-Zener Transitions Through Small Electronic 
Eigenvalue Gaps in the Born-Oppenheimer Approximation
(118K, Latex)

ABSTRACT.  We study the propagation of molecular wave packets through the simplest two 
types of avoided crossings of electronic energy levels in a limit where the gap 
between the eigenvalues shrinks as the nuclear masses are increased. For these 
types of avoided crossings, the electron energy levels essentially depend on only 
one of the nuclear configuration parameters, as is the case for all diatomic molecules. 
We find that the transition probabilities are of order 1 and are determined by the 
Landau-Zener formula.