Has QTPIE ever been applied to 1D metals such as polyacetylene?
How flattering that someone asked this question ;)

The short answer is yes, I've tried QTPIE on series of conjugated molecules like the oligoacetylenes and oligoacenes. The results, however, are fairly dismal, as can be seen in the preprint. The problem is that in these empirical charge models, the polarizability grows faster than the size of the molecule, which means that these models predict infinite polarizabilities and charge transport behavior for bulk materials, which is obviously nonsense.

The problem is quite intimately related to that of self-interaction error in approximate density functional theories, which also exhibit similar problems.