High-Precision Cross Sections for Electron-Atom Collisions in Laser and Lighting Applications*

In recent years, much progress has been achieved in calculating reliable cross-section data for electron scattering from atoms and ions. In particular, the ``convergent close-coupling'' (CCC) [1] and \hbox{``$R$-matrix} with pseudo-states'' (RMPS) [2] methods have been extremely successful in describing elastic scattering as well as electron-impact excitation and ionization of light quasi-one and quasi-two electron targets, such as atomic hydrogen, helium, the alkalis, and the alkali-earth elements. However, accurate calculations of electron collisions with more complex targets, notably the heavy noble gases Ne$-$Xe, heavy quasi-one electron targets such as Zn, Ba, or Hg, and transition metals such as Fe or Mo~[3], continue to be a major challenge. We have recently further developed a new version of the $R$-matrix (close-coupling) method, using a $B$-spline basis with non-orthogonal sets of term-dependent orbitals~[4]. This method allows us to generate target descriptions of unprecedented accuracy in collision calculations. Example results~[5-7] for some of the systems mentioned above illustrate that the flexibility of the $B$-spline $R$-matrix (BSR) method to describe both the $N$-electron target and the ($N\!+\!1$)-electron collision problems is of crucial importance for obtaining highly accurate cross sections, particularly in the low-energy near-threshold regime, which is often dominated by resonance structure. \newline \newline [1] I. Bray, D.V. Fursa, A.S. Kheifets, and A.T. Stelbovics, J. Phys. B {\bf 35} (2002) R117.\newline [2] K. Bartschat, Comp. Phys. Commun. {\bf 114} (1998) 168.\newline [3] K. Bartschat, in {\it Atomic and Molecular Data and Their Applications}, D.R. Schultz, P.R. Krstic, and F. Owbny (eds.), AIP Conf. Proc. \#636 (2002) 192.\newline [4] O. Zatsarinny and C. Froese Fischer, J.~Phys. B~{\bf 33} (2000) 313.\newline [5] O. Zatsarinny and K. Bartschat, J.~Phys. B~{\bf 37} (2004), 2173 and 4693.\newline [6] O. Zatsarinny and K. Bartschat, Phys. Rev. A {\bf 71} (2005), 022716.\newline [7] O. Zatsarinny, K. Bartschat, L. Bandurina, and V. Gedeon, Phys. Rev. A {\bf 71} (2005) 042702.