Electron affinity and photodetachment calculations of Nd$^-$

Our recent relativistic configuration-interaction (RCI) calculations for the bound states of Ce$^-$\footnote{S. M. O'Malley and D. R. Beck, Phys. Rev. A {\bf 74}, 042509 (2006).} have shown the usefulness of analysis which combines calculated photodetachment cross sections with experimental measurements \footnote{V. T. Davis and J. S. Thompson, Phys. Rev. Lett. {\bf 88}, 073003 (2002).}. Here we present RCI results for 8 weakly bound ($\leq$ 0.2 eV) states of Nd$^-$ ($6p$ attachments to $4f^46s^2$). Photodetachment cross sections involving excited states of Nd {\sc i} are expected to resolve the discrepancy with the available experimental electron affinity of 1.916 eV \footnote{V. Davis and J. Thompson, Bull. Am. Phys. Soc. {\bf 48}, 98 (2003).}. Additional improvements of our methodology are also discussed.