Orthogonalized-Plane-Wave Band Structure of Polymeric Sulfur Nitride,(SN)x

We present the first orthogonalized-plane-wave band structures and corresponding densities of states for two reported crystal structures of polymeric surfur nitride, ${\left(\mathrm{SN}\right)}_x$, and compare our results with experiment. We examine the band structures in light of the low-temperature stability of the metallic and superconducting states in ${\left(\mathrm{SN}\right)}_x$ and conclude that this stability derives from closed Fermi surfaces introduced by electronic interchain coupling.