Glide-Plane Symmetry and Superconducting Gap Structure of Iron-Based   Superconductors
  We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories have proposed that so-called $\eta$-pairing states with nonzero total momentum can be realized and possess exotic properties such as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that $\eta$ pairing is inevitable when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in $z$; however, by explicit calculation, we conclude that the gap function that appears in observable quantities is identical to that found in earlier, 1 Fe per unit cell pseudocrystal momentum calculations. 
Y. Wang, T. Berlijn, P. J. Hirschfeld, D. J. Scalapino, and T. A.   Maier
cond-mat.supr-con