  The electronic structural properties in the presence of constrained
magnetization and a charged background are studied for a monolayer of FeSe in
non-magnetic, checkerboard-, and striped-antiferromagnetic (AFM) spin
configurations. First principles techniques based on the pseudopotential
density functional approach and the local spin density approximation are
utilized. Our findings show that the experimentally observed shape of the Fermi
surface is best described by the checkerboard AFM spin pattern. To explore the
underlying pairing mechanism, we study the evolution of the non-magnetic to the
AFM-ordered structures under constrained magnetization. We estimate the
strength of electronic coupling to magnetic excitations involving an increase
in local moment and, separately, a partial moment transfer from one Fe atom to
another. We also show that the charge doping in the FeSe can lead to an
increase in the density of states at the Fermi level and possibly produce
higher superconducting transition temperatures.
