  Pyrochlore oxides are fascinating systems where strong, multi-orbital
correlations in concert with geometrical frustration give rise to unanticipated
physical properties. The detailed mechanism of the insulator-metal transitions
(IMT) underpinning these phenomena is, however, ill-understood in general.
Motivated thereby, we study the IMT in the pyrochlore ${\rm Hg_{2}Ru_{2}O_{7}}$
using LDA+DMFT. In contrast to the well-known examples of Mott transitions in
TMO, we show that, in the negative charge-transfer situation characteristic of
\hg, self-doping plays a crucial role in the emergence of an orbital-selective
IMT. We argue that this mechanism has broader relevance to other correlated
pyrochlore oxides.
