Calculation of Electron Affinity and Partial Cross Sections of Hf$^-$

We have calculated for the first time the electron affinity (EA) of Hf$^-$, using the relativistic configuration interaction method. Our calculations show Hf$^-$ has only one bound state 5d$^2$6s$^2$6p $J$=5/2, which is a 6p attachment to the ground state of Hf I. By combining our valence stage result with the separate estimate for the modest core-valence contribution, the EA of Hf$^-$ is about 0.114 eV. So far there have been only two experimental results [1,2] for the EA of Hf$^-$, but both gave only the limits. Our result falls within both of the limits. We also calculate the partial cross sections for photodetachment to the lower lying neutral thresholds. [1] M-J. Nadeau {\em et al}, Nucl. Instr. and Meth. B {\bf 123}, 521 (1997) [2] Vernon T. Davis {\em et al}, Nucl. Instr. and Meth. B {\bf 241}, 118 (2005)