First-principles investigation of CuO decomposition and its transformation into <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Cu</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">O</mml:mi></mml:mrow></mml:math>

This paper reports on the mechanisms of CuO decomposition and its associated phase transformation into ${\mathrm{Cu}}_{2}\mathrm{O}$, as a fundamental step thermite materials reaction, where serves oxidizer. The Frenkel pair defects in perfect bulk show extremely high formation energy (&gt;4 eV) indicating that initiates at defects/interfaces/surfaces, latter being sensitive to surface orientation. In contrast variety surfaces [(111), (110), ($10\overline{1}$)] exhibiting three-fold coordinated oxygen atoms, results vacancy requires higher disordered surfaces, such CuO(001), which activation is reduced 1.31 eV. leads exothermic chemisorbed O-O peroxy-bridge complex (\ensuremath{-}1.25 eV adsorption) thermodynamically moderates backreaction (vacancy annihilation). Further desorption molecular necessitates an 1.53 eV, compatible with observed experimentally 600 K (\ensuremath{\sim}second process duration). As driving mechanism release upon decomposition, migrations close towards are determined for number crystalline directions orientations considerable anisotropy, two preferential directions: [110] [001] 1.35 1.77 activation, lowered 1.08 1.03 when approaching (111) (001) respectively. Finally, ${\mathrm{Cu}}_{2}\mathrm{O}$ follows two-step process: first structural modification from monoclinic orthorhombic takes place has lost 12.5% followed by barrierless transition cubic 44--48% atoms have been removed, i.e., very stoichiometric ${\mathrm{Cu}}_{2}\mathrm{O}$.