  \'Eliashberg theory, being generalized to the electron-phonon (EP) systems
with not constant density of electronic states, as well as to the frequency
behavior of the renormalization of both the electron mass and the chemical
potential, is used to study hydrogen sulphide phase under pressure. The phonon
contribution to the anomalous electron Green's function (GF) is considered. The
pairing is considered within the overall width of the electron band, and not
only in a narrow layer at the Fermi surface. The frequency and the temperature
dependences of the electron mass renormalization ReZ , the density of
electronic states , renormalized by the EP interaction , the spectral function
of the electron-phonon interaction, obtained by calculation are used to
calculate the electronic abnormal GF. The \'Eliashberg generalized equations
with the variable density of electronic states are resolved. The dependence of
both the real and the imaginary part of the order parameter on the frequency in
the phase is obtained. The value in the hydrogen sulfide phase at the pressure
P = 225 GPa has been defined.
