  Using LDA+GTB (local density approximation+generalized tight-binding) hybrid
scheme we investigate the band structure of the electron-doped high-$T_c$
material Sm$_{2-x}$Ce$_{x}$CuO$_4$. Parameters of the minimal tight-binding
model for this system (the so-called 3-band Emery model) were obtained within
the NMTO ($N$-th order Muffin-Tin orbital) method. Doping evolution of the
dispersion and Fermi surface in the presence of electronic correlations was
investigated in two regimes of magnetic order: short-range (spin-liquid) and
long-range (antiferromagnetic metal). Each regime is characterized by the
specific topologies of the Fermi surfaces and we discuss their relation to
recent experimental data.
