The R-matrix theory of electron-atom scattering using the Dirac Hamiltonian

The R-matrix theory of electron-atom scattering using the Dirac Hamiltonian is formulated in a similar way to that used in the non-relativistic case. The expression for the R-matrix in terms of the surface amplitudes is exactly the same, but the boundary condition at r=a for the continuum orbitals is modified. The matching process at the boundary gives the K matrix, from which the S matrix and cross sections can be derived. A general computer program implementing this procedure is now being written.