  Xenon, which is quite inert under ambient conditions, may become reactive
under pressure. The possibility of formation of stable xenon oxides and
silicates in the interior of the Earth could explain the atmospheric missing
xenon paradox. Using the ab initio evolutionary algorithm, we predict the
thermodynamical stabilization of Xe-O compounds at high pressures (XeO, XeO2
and XeO3 at pressures above 83, 102 and 114 GPa, respectively). Our
calculations indicate large charge transfer in these oxides, suggesting that
large electronegativity difference and pressure are the key factors favoring
the formation of xenon compounds. Xenon compounds in the Earth's mantle,
however, cannot directly explain the missing xenon paradox: xenon oxides are
unstable in equilibrium with metallic iron in the Earth's lower mantle, while
xenon silicates are predicted to spontaneously decompose at all mantle
pressures (<136 GPa). This does not preclude Xe atoms from being retained in
defects of mantle silicates and oxides.
