  We describe, within an ab-initio approach, the stabilization of the
tetragonal phase vs. the monoclinic one in Yttrium-doped Zirconia. The process
is believed to be influenced from different mechanisms. Indeed we show that
there is a delicate balance between the change in electrostatic and kinetic
energy and exchange-correlation effects. In the tetragonal phase the
perturbation induced by doping is better screened at the price of sacrificing
correlation energy. Our work opens the opportunity to use the same approach to
predict the tetragonal phase stabilization of materials like Zirconia or
Hafnia, with different and less characterized dopants.
