B-Spline Breit-Pauli R-matrix calculations for electron collisions with Krypton and Xenon.

We have extended our previous work on electron collisions with Ne~[1] and Ar~[2] to the heavier noble gas targets Kr and Xe. In our $B$-Spline $R$-matrix method~[3,4], relativistic effects are accounted for through the most important terms of the Breit-Pauli hamiltonian in the inner region of the $R$-matrix box. Several sets of non-orthogonal valence orbitals were employed to account for the strong term dependence in the one-electron orbitals. Using non-orthogonal basis sets avoids the need for pseudo-orbitals to improve upon the target description and virtually eliminates pseudo-resonance problems. The agreement between our predictions and experiment~[5] is much better than obtained in previous calculations based on the standard $R$-matrix approach with strictly orthogonal orbitals, particularly in details such as resonance positions and widths. Consequently, the new results are expected to represent a significant improvement of the current database for electron collisions with heavy noble gases. \par\noindent [1] O. Zatsarinny and K. Bartschat, J. Phys. B {\bf 37} (2004) 2173. \par\noindent [2] O. Zatsarinny and K. Bartschat, J. Phys. B {\bf 37} (2004) 4693. \par\noindent [3] O. Zatsarinny and C. Froese Fischer, J. Phys. B {\bf 33} (2000) 313. \par\noindent [4] O. Zatsarinny, Comp. Phys. Commun. {\bf 174} (2006) 274. \par\noindent [5] S.J. Buckman and C.W. Clark, Rev. Mod. Phys. {\bf 66} (1994) 539.