Application of first-principles methods for the calculation of the crystal and electronic structure of oxynitrides

Theoretical simulations using Density Functional Theory (DFT) within ab initio total-energy and molecular-dynamics method have been performed for several oxynitride materials. Examples dealt with are compounds in the Ta-O-N, Si-O-N and Al-O-N systems. Random or partially ordered distributions of the oxygen and nitrogen ions as well as other structural defects can be predicated very well by these methods. Local structure relaxation and its influence on the electronic properties are addressed.