  The van-der-Waals gap of iron chalcogenide superconductors can be
intercalated with a variety of inorganic and organic compounds that modify the
electron doping level of the iron layers. In Lix(C3N2H10)0.37FeSe, a dome in
the superconducting transition temperature Tc has been reported to occur in the
doping range of x=0.06 to x=0.68. We use a combination of density functional
theory and spin fluctuation theory to capture the evolution of superconducting
transition temperatures theoretically. We clearly demonstrate how the changing
electronic structure supports an increasing superconducting Tc. The suppression
of Tc at high doping levels can, however, only be understood by analyzing the
magnetic tendencies, which evolve from stripe-type at low doping to bicollinear
at high doping.
