The role of the bond midpoint electron density in homonuclear molecular binding

Electron density theory is first employed to express the potential energy curve of the H   2 +molecular ion in terms of bond midpoint properties. For heavy homonuclear diatomics, low‐ordr density gradient theory is used, but now for the chemical potential, with a similar conclusion to that for H   2 + . Homonuclear clusters of alkali atoms are then treated in some detail. Finally the dissociation of doubly charged clusters is considered, by a study of supermolecular treated in some detail. Finally the dissociation of doubly charged clusters is considered, by a study of supermolecular ions (Na   20 + ) 2 and (K   20 + ) 2 , again using a density gradient expansion in low order. The deviation between the barrier for fission and the Coulomb barrier is linear in the bond midpoint density over a substantial range of fragment separation. © 1994 John Wiley & Sons, Inc.