Channel-coupling theory of covalent bonding inH2: A further application of arran channel quantum mechanics

The dissociation energy $D_e$ and the equilibrium proton-proton separation $D_{\mathrm{eq}}$ of ${\mathrm{H}}_2$ are calculated using the methods of arrangement-channel quantum mechanics. This theory is the channel component version of the channel-coupling array approach to many-body scattering, applied to bound-state problems. In the approximation used herein, the wave function is identical to that of the classic Heitler-London-Sugiura valence-bond calculation, which gave $D_e=3.14\mathrm{}$ eV and $R_{\mathrm{eq}}=1.65\mathrm{}{a}_0$, values accurate to 34% and 17.8%, respectively. The present method yields $D_e=4.437\mathrm{}$ eV and $R_{\mathrm{eq}}\simeq 1.42a_0$, accurate to 6.5% and 1%, respectively. Some implications of these results are discussed.