The differential and total cross sections for the formation of positronium in its ground state from Li and Na atoms by the impact of intermediate-energy positrons are calculated in the first Born and distorted-wave Born approximations. Hellmann-type pseudopotentials are used to represent the alkali-metal ion cores. The difference in the use of pseudopotentials and the static potential for the core representation for evaluating various rearrangement cross sections is discussed.
Nahar SN, Wadehra JM. Positronium formation from Li and Na atoms by use of pseudopotentials. Phys. Rev. A. 1986;35(11):4533-4540. doi: 10.1103/PhysRevA.35.4533