  The electronic energy band spectra, as well as partial and total density of
electronic states of the crystal argyrodite Ag$_{8}$SnSe$_{6}$ have been
evaluated within the projector augmented waves (PAW) approach by means of the
ABINIT code. The one-electron energies have been evaluated using two
functionals for exchange-correlation energy. The first one is the generalized
gradient approximation (GGA) approach. The second one is the hybrid functional
PBE0 composed of the semilocal GGA part and Hartree-Fock exact exchange
non-local energy for strongly correlated $4d$ electrons of Ag atom. The second
approach eliminates the Coulomb self-interaction of the Ag $4d$ electrons. This
leads to a significant restructuring of the energy bands in the filled valence
part and to an improved location of the Ag $4d$-states on the energy scale, and
the resulting value of the band gap is well compared with experiment. The
effects of strong correlation on the electronic structure of the crystal
argyrodite are considered here for the first time.
