Proton-Hydrogen Collisions: Molecular Treatment of theH(2p)Excitation

The molecular treatment of the reaction $p+\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}\to p+\mathrm{H}\mathrm{}\left(2p\right)\mathrm{}$ has been reexamined. Exact ${\mathrm{H}}_2^{+}$ wave functions and dynamic coupling elements have been calculated and used throughout. Two- and four-state calculations have been carried out in the range 0.1-16 keV and compared with previous theoretical and experimental findings. The results support the validity of the molecular approach at higher velocities than previously considered. A new basis set, rather than translational factors, eliminates spurious asymptotic radial coupling inherent in the Born-Oppenheimer basis.