The Diatomic Energy Curve

The point-charge density increases monotonically with decreasing d until it reaches a maximum at the critical ratio of d/r = r. At this point e = 0.5513 and 

An additional factor must be taken into account for bonds involving hydrogen, i.e. the depth to which the hydrogen sphere penetrates into the ionization sphere of the second atom. The relationship between dimensionless interatomic distance and dissociation energy, in this case, is summarized 

---