Convergence of the Hydrogenic Expansion in H+–H Scattering

Calculations have been carried out for the processes $$\begin{array}{c}{\mathrm{H}}^{+}+\mathrm{H}\mathrm{(nl)\to }\mathrm{H}\mathrm{(nl)+}{\mathrm{H}}^{+}\\ \to {\mathrm{H}}^{+}+\mathrm{H}\mathrm{(nl)}\end{array}$$ using a two‐centered expansion in travelling‐wave hydrogen orbitals. New four‐state calculations were done with 1s, 2s, 2p₀ and 2p₁ states included. After taking proper account of the asymptotic coupling between states, our cross sections are in close agreement with those of Cheshire, Gallaher, and Taylor. In addition, seven‐state calculations were performed by including the 3s, 3p₀, and 3p₁ states. A comparison of four‐ and seven‐state results shows that the convergence of the cross sections for the n=2 states appears to be fairly rapid.