Nuclear quadrupole moment of the Tc-99 ground state

By combining first-principles calculations and existing nuclear magnetic resonance (NMR) experiments, we determine the quadrupole moment of the 9/2(+) ground state of Tc-99 to be (-)0.14(3)b. This confirms the value of -0.129(20)b, which is currently believed to be the most reliable experimental determination, and disagrees with two earlier experimental values. We supply ab initio calculated electric-field gradients for Tc in YTc2 and ZrTC2. If this calculated information would be combined with yet to be performed Tc-NMR experiments in these compounds, the error bar on the Tc-99 ground state quadrupole moment could be further reduced.