Knowledge Bank

A simple quantum mechanical model of bond formation is presented which allows the derivation of an internuclear potential function of the form {V}={-}{D}{e}{e}^{-{n}\Delta{R}^{2}/2{R}}\mbox{ where }{n}={k}{e}{R}{e}/{D}_{e}. The method makes use of a delta function model whereby bond formation is described by the shifting of atomic delta functions into molecular delta functions. The predicted results for $H2+$ are nearly exact for all bond properties while the results for $H2$ are more accurate than those of all but the most elaborate methods used previously. In particular the method appears superior to both the valence bond and molecular orbital theories in both results and ease of calculation. Advantages of the method are that the same form for the inter-nuclear potential is obtained for polyelectronic bonds as for one and two electron bonds, and that polyelectronic bond systems can be handled by one-dimensional methods. Theoretical values for the parameter, n, for polyelectronic molecules are calculated which agree well with values obtained from experimental data. Application to the excited states of $H2$, $He2$ and $He2+$ gives good results.