Positron Collisions with Atoms and Ions

2DRMP: A suite of two-dimensional R-matrix propagation codes

“…The interaction between the projectile and the target, V i j is given by the electrostatic multipole expansion (see Eq. (7.33) of [26]), …”

“…This correction is dependent on the channel energy. However, since the correction is slowly varying with respect to channel energy it is approximated by a quadratic using a least squares fit across a range of energies (see Section 7.4.1.5 of [26]…”

“…The second approach is the Intermediate Energy R-matrix Method (IERM) [25]. To date this method has only been implemented for one-electron targets [26] where the distinctive feature is that both electrons are treated identically and the R-matrix basis states are constructed to allow for both electrons to be in the continuum. The IERM approach results in a more densely packed pseudostate basis, with respect to the target state energy levels, than the RPMS basis.…”