On the Formation of Transient (Na$_{19}$)$_2$ and (Na$_{20}$)$_2$   Cluster Dimers from Molecular Dynamics Simulations
  By using tight binding molecular dynamics simulations, we discuss the possibilities to form (Na$_{19}$)$_2$ and (Na$_{20}$)$_2$ cluster dimers in sodium cluster collisions. In the case of Na$_{19}$ + Na$_{19}$, we show that the formation of a prolate dimer-like (Na$_{19}$)$_2$ maybe depend on the initial relative orientations of the colliding clusters. A similar study for Na$_{20}$ + Na$_{20}$ does not seem to show the same dependence on the initial orientations in the formation of the (Na$_{20}$)$_2$ cluster dimer. 
F.S. Zhang, F. Spiegelmann, E. Suraud, V. Fraysse, R. Poteau, R.   Glowinski and F. Chatelin