  The deformation-induced splitting of isoscalar giant monopole resonance
(ISGMR) is systematically analyzed in a wide range of masses covering medium,
rare-earth, actinide, and superheavy axial deformed nuclei. The study is
performed within the fully self-consistent quasiparticle
random-phase-approximation (QRPA) method based on the Skyrme functional. Two
Skyrme forces, one with a large (SV-bas) and one with a small (SkP) nuclear
incompressibility, are considered. The calculations confirm earlier results
that, due to the deformation-induced E0-E2 coupling, the isoscalar E0 resonance
attains a double-peak structure and significant energy upshift. Our results are
compared with available analytic estimations. Unlike earlier studies, we get a
smaller energy difference between the lower and upper peaks and thus a stronger
E0-E2 coupling. This in turn results in more pumping of E0 strength into the
lower peak and more pronounced splitting of ISGMR. We also discuss widths of
the peaks and their negligible correlation with deformation.
