Peierls Instability in Carbon Nanotubes

We present a first-principles study of Peierls distortions in \emph{trans}-polyacetylene, polyacene, and armchair $(n,n)$ carbon nanotubes. Our findings suggest that the ground-state geometries of armchair $(n,n)$ carbon nanotubes, with $n$ up to 6, exhibit a Peierls distortion as it is found for \emph{trans}-polyactetylene. In contrast to previous studies in which no Peierls distortion is found with conventional local and semi-local density functionals, we use a hybrid functional whose exact-exchange admixture has been specifically optimized for the problem at hand.