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The native point defects and mechanism of accommodating deviations from stoichionnetry Of Si(2)N(2)O crystal have been investigated using atomistic simulation techniques. This work firstly provides a reliable classical interatomic potential model derived from density functional theory calculations. The force-field parameters well reproduce the crystal structure, elastic stiffness, and dielectric constants of Si(2)N(2)O. It is expected that the force-field parameters are useful in future investigations on Si(2)N(2)O by molecular dynamic simulation. The calculated formation energies for native defects suggest that intrinsic disorder in stoichiometric Si(2)N(2)O is dominated by antisites and a degree of oxygen Frenkel defect may also exist in this system. In nonstoichiometric Si(2)N(2)O, the calculated reaction energies indicate that excess SiO(2) or Si(3)N(4) is most likely accommodated by the formation of antisite in the lattice. And we also find that SiO(2) excess is energetically more favorable than Si(3)N(4) Surplus in Si(2)N(2)O. (C) 2009 Elsevier Ltd. All rights reserved.