PROTON-HYDROGEN SCATTERING WITH VARIABLE EFFECTIVE CHARGE

Coupled-channel calculations are performed for proton-hydrogen scattering using an expansion in atomic orbitals in which the effective charge seen by each orbital is allowed to vary with time. It is shown that optimum charges are determined by an Euler-Lagrange equation. At very low energies the method closely resembles an expansion in molecular orbitals, and the Euler-Lagrange equation minimizes the molecular energies. By comparison with previous calculations which use molecular and atomic expansions it is shown how the method bridges the gap between them. Excellent agreement is obtained with the oscillating probability measurements of Lockwood and Everhart for charge exchange at 3°. Cross sections are calculated at 25 kev and compared with experiment and other theories.